How buddha came back to his human consciousness if consciousness and fabrication ceases after release

Is there any sutta where buddha talked about such healthy ego (Like, "If I try I can learn it or do it etc").

Perhaps the Bikkhuni sutta.

See for example here and here for a description of what "pride" or "conceit" are.

I think that's equivalent to what people often understand as "ego".

The Bikkhuni sutta (AN 4.159) says that conceit ("ego"?) can be useful on the path, even though it's eventually to be abandoned.

This body comes into being through conceit. And yet it is by relying on conceit that conceit is to be abandoned.' Thus was it said. And in reference to what was it said? There is the case, sister, where a monk hears, 'The monk named such-and-such, they say, through the ending of the fermentations, has entered & remains in the fermentation-free awareness-release & discernment-release, having known & realized them for himself in the here & now.' The thought occurs to him, 'The monk named such-and-such, they say, through the ending of the fermentations, has entered & remains in the fermentation-free awareness-release & discernment-release, having known & realized them for himself in the here & now. Then why not me?' Then he eventually abandons conceit, having relied on conceit. 'This body comes into being through conceit. And yet it is by relying on conceit that conceit is to be abandoned.' Thus was it said, and in reference to this was it said.

I understand/paraphrase that as, "He practices with such-and-such result. Why can't I?" That's a comparison, therefore a conceit. But it's a constructive or beneficial comparison, e.g. to learn by comparison with someone else's (superior) practice.

I must add that this sutta was spoken by Ananda, not the Buddha.

Actually there's a lot of doctrine about "trying" -- that's "effort" isn't it, so see doctrine about "Right Effort" -- see also Vīrya and so on.

See also "faith", conviction, confidence (saddhā).

Consciousness is an element among elements conceived & perceived in the world; arises & ceases in the world.

When talking about cessation of perception & feeling it is said;

How many ,conditions are there for the attainment of the theme-less awareness-release?"

"There are two conditions for the attainment of the theme-less awareness-release: lack of attention to all themes and attention to the theme-less property. These are the two conditions for the attainment of the theme-less awareness-release

"There are three conditions for the persistence of the theme-less awareness-release: lack of attention to all themes, attention to the theme-less property, and a prior act of will. These are the three conditions for the persistence of the theme-less awareness-release."

"And how many conditions are there for the emergence from the theme-less awareness-release?"

"There are two conditions for the emergence from the theme-less awareness-release: attention to all themes and lack of attention to the theme-less property. These are the two conditions for the emergence from the theme-less awareness-release."https://www.accesstoinsight.org/tipitaka/mn/mn.043.than.html

Citta asked him a further question: "Now, how does emergence from the cessation of perception & feeling come about?"

"The thought does not occur to a monk as he is emerging from the cessation of perception & feeling that 'I am about to emerge from the cessation of perception & feeling' or that 'I am emerging from the cessation of perception & feeling' or that 'I have emerged from the cessation of perception & feeling.' Instead, the way his mind has previously been developed leads him to that state."

"[...] Citta asked him a further question: "When a monk is emerging from the cessation of perception & feeling, which things arise first: bodily fabrications, verbal fabrications, or mental fabrications?"

"When a monk is emerging from the cessation of perception & feeling, mental fabrications arise first, then bodily fabrications, then verbal fabrications." https://www.accesstoinsight.org/tipitaka/sn/sn41/sn41.006.than.html

On this ground it can be asserted that the duration of the cessation attainment is determined not whilst being percepient of Nibbana but due to a prior act of will and no later than entering.

having directly known the extent of what has not been experienced through the allness of the all, I wasn't the all, I wasn't in the all, I wasn't coming forth from the all, I wasn't "The all is mine." I didn't affirm the all.https://www.accesstoinsight.org/tipitaka/mn/mn.049.than.html

In regards to this it can be asserted that the knowledge spoken about is associated with a meditative attainment on the treshold of supramundane, seeing with wisdom leading to destruction of taints.

Then it can be held that the determination for the duration is an act of will, an occurence in the world, it is included in the allness of the all and isn't made outside of it.

This interpretation holds that emptiness, undirected and theme-less awareness releases are classifications of the cessation of perception & feeling release by which taints are destroyed, are attainments on the treshold of the destruction of taints and the difference is in how they are apprehended in dependence on the perceptions that one developed culminating in the unsurpassed release.

Here from Thanissaro's footnotes to sn41.6;

Emptiness, the signless, & the undirected are names for a state of concentration that lies on the threshold of Unbinding. They differ only in how they are approached. According to the commentary, they color one's first apprehension of Unbinding: a meditator who has been focusing on the theme of inconstancy will first apprehend Unbinding as signless; one who has been focusing on the theme of stress will first apprehend it as undirected; one who has been focusing on the theme of not-self will first apprehend it as emptiness. This is a pali sutta only interpretation favor by commentary.

I assume this is close to the expression of Mahasi Sayadaw's "Manual of Insight" and still a popular burmese/sri lankan theravadin expression and maybe analysis.

As i ubderstand it; Suppose 'x' is thought of as a single element, a whole of many sub-elements perceived & conceived in and by itself, X within X is known to be an autonomous self-sustaining, self-creating & self-directing sub-system in and by itself.

Suppose the sub system X, is called thus within Itself because it is not the only element to be known as there is another element which isn't part of the sub-system X, call it Y, which can be known as a truth because cessation of perception is discerned in X in dependence on it. Knowledge of Y can thus appear as an element included in X if an element of perception within has been directed to cessation.

The factors for arising, persistence & the cessation of the perception of X are included in what is X and are not Y.

After complete cessation of consciousness, how did the Buddha come back to human consciousness? If he can come back, isn't it not a complete release?

The Pali word "nirodha" (often translated as "cessation") does not necessarily mean "destruction".

Also, in the teaching about the stopping of Dependent Origination, the cessation of consciousness refers to the cessation of a consciousness arising from ignorance. It does not refer to the stopping of a consciousness unaffected by ignorance. Refer to SN 22.53.

Other suttas that explain consciousness does not end with enlightenment include SN 12.44, MN 148 and the end part of MN 38.

And that state is just like the Dimension of Nothingness, or the Dimension of Neither Perceptions nor Non--perceptions. So if craving again develops, then there may be chance of becoming.

The above is irrelevant.

And one more question I would like to ask: Buddha gave a not-self strategy

Bhikkhu Thanissaro book on "not-self strategy" is wrong and has been debunked many times.

to deal with five aggregates by considering them as not-self

Regarding aggregates as not-self means there is no selfishness therefore automatic goodness.

but as human being I think we do require a healthy ego of will power and idea of 'self' (Like, "If I try I can learn it or do it etc"). Is there any sutta where buddha talked about such healthy ego?

Ego is irrelevant. To have a healthy mind requires having morality.

This said, the Buddha refers to the healthy ego in a 'conventional' manner in the Attavagga.

Note: Buddha avoided such type of questions because this stop us from direct knowing, but I am asking due to curiosity; but do reply to my second question.

The Buddha did not ignore any right proper questions. Bhikkhu Thanissaro book on "not-self strategy" is wrong and has been debunked many times. It is best ignored. This will result in not troubling Buddhists by asking confused questions about it. Bhikkhu Thanissaro's heretical book on "not-self strategy" is a misunderstanding of the sutta SN 44.10, where Vacchagotta,using self-view, asked two questions: "Do I have a self". "Do I have no self?". Both of these questions was wrong because both of the questions assumed the existence of an "I".

QN 1: After complete cessation of consciousness, how did the Buddha come back to human consciousness? If he can come back, isn't it not a complete release?

Well, there is such a thing as clinging aggregates. According to this answer, for a living arahant, when ignorance is uprooted, this breaks dependent origination, that ends craving, clinging and suffering. In the chain of dependent origination, clinging aggregates would also cease.

The living arahant according to Iti 44, attained nibbana with fuel remaining (sa-upadisesa), meaning the non-clinging aggregates are still functioning like glowing embers, although the fires of passion, aversion and delusion have ceased.

Parinibbana is when the non-clinging aggregates stop functioning. This is nibbana without fuel remaining (anupadisesa) according to Iti 44.

So, the answer to this question is that upon attaining nibbana, the Buddha experienced complete cessation of clinging consciousness, but non-clinging consciousness remained functional for the rest of his human life. The five aggregates that are referred to in dependent origination is clinging aggregates (including consciousness), and not non-clinging aggregates.

In other words, upon nibbana, an arahant has complete cessation of clinging.

QN 2: And is it possible to have complete release through jhana only by ceasing craving, fabrication etc without gaining insight of nirvana.

No. It's quite possible to cling to the pleasures of jhanas and get one's mind stuck, as seen in MN 138:

And how is their consciousness stuck internally? Take a mendicant who, quite secluded from sensual pleasures, secluded from unskillful qualities, enters and remains in the first absorption, which has the rapture and bliss born of seclusion, while placing the mind and keeping it connected. Their consciousness follows after that rapture and bliss born of seclusion, tied, attached, and fettered to gratification in that rapture and bliss born of seclusion. So their mind is said to be stuck internally.

And the sutta continues about the higher jhanas.

QN 3: Buddha stated in many suttas that five aggregates are not-self; but as human being we do require idea of self (identity or ego) and will power (self-esteem).

In a sense, you can use the idea of self in a skillful way (as long as you have not dropped self-view) as shown in AN 5.57 below:

“And for the sake of what benefit should a woman or a man, a householder or one gone forth, often reflect thus: ‘I am the owner of my kamma, the heir of my kamma; I have kamma as my origin, kamma as my relative, kamma as my resort; I will be the heir of whatever kamma, good or bad, that I do’? People engage in misconduct by body, speech, and mind. But when one often reflects upon this theme, such misconduct is either completely abandoned or diminished. It is for the sake of this benefit that a woman or a man, a householder or one gone forth, should often reflect thus: ‘I am the owner of my kamma, the heir of my kamma; I have kamma as my origin, kamma as my relative, kamma as my resort; I will be the heir of whatever kamma, good or bad, that I do.’

Also, please see Attakari Sutta.