what to do, when you can't meditate?

I recommend you to download some musics like flow of water or chanting of om or music with slow beats.
And you try to meditate only by listening to the music and soon you will get the good concentration.

After a stressful or difficult day, either from work or daily activity that makes the practice of mindfulness difficult, return to mindfulness as soon as possible. Either during your method of returning home or once you get home. Increase your effort towards mindfulness sincerely and wholly as soon as possible. This will begin the process of bringing you back to being in the moment and starts calming the mind prior to formal or sitting meditation. One might refer to the mindful process I described as meditation. The method I offer is an alternative to say, walking into your meditation room, with your mind agitated and attempting to immediately sit down, meditate and calm the mind. As suggested in a previous post walking meditation can assist with this same purpose prior to taking to your cushion. As well, one may begin formal or sitting meditation with body-sweeping to calm the mind and bring the mind within. With wishes for peace to all.

For various reasons -- when I am unable to practice my regular meditation (mindfulness of breathing anapanasati) well, I take on one of three responses:

1) I make my focus my state of dissatisfaction with the meditation my object: Here is a thought, there is a responding mental painful feeling, here is aversion, here is craving for it to be different. Here is me grasping at some effort to create change, here is the result, here it goes again. The constant succession of conditioned links is beautiful and terrible to behold. One does lose enchantment with this experience pretty quickly, and wants no more. It is not a comfortable practice but it is an "enlightening" one if I mayuse the term without intending full liberation. I think it does move you closer to that though.

2) I switch to one that is easier because it feels good and soothes painful mental states: Metta, or more properly Brahma Viharra , any of the well recognized teachers does well with this, but my favorite guidance for this particular one is the anupada sutta dhamma talk by Bhante Vimalaramsi.

3) I switching to living life meditation, just begin my next tasks, whi8le holding the old meditation object in mind or the new one. When I absolutely can't seem to hold one, I use the reflection on Buddha Dhamma, Sangha that I put to chanting tune.

Good luck. I think we have all been there Iknow I have been.

Try this exercise I learned from that book "The Power of Concentration":

• Stare at an object (like a door knob) for 10 full minutes
• Focus on keeping your body perfectly still
• Do not let other thoughts drift in

Do this exercise for 6-7 days and you will see that your body control and concentration would've improved, you will find it easy to relax, concentrate, and not be disturbed.

Do you have a general technique which, if you remember it, you've discovered that it helps to alleviate hindrances?

For example someone referenced the Nissaraniya Sutta recently, which mentions six "means of escape". From this list, for example, perhaps if you remembered "good will", then might that remembrance be enough to escape a hindrance? Or "non-self"? Or perhaps other teachings not on this list, would it help to remember "impermanence" for example, or a doctrine about "craving"?

If there are doctrines like that, which you find helpful when you remember them --if you want to remember them but don't-- then might a memory-aid (a semi-permanent sense-object) be useful? A little stone to hold in your hand, or the right word written on a piece of paper?

Or how about moving to a different type of meditation, e.g. "awareness of the breath", if there's too much turmoil for another kind of meditation?

Or I think that each of the formal hindrances have corresponding canonical techniques to counter them, for example The Five Mental Hindrances and Their Conquest references suttas which have advice for how to "denourish" each hindrance.

Or I think that meditation teachers (here is just one example) suggest you investigate the hindrance, as being a mental phenomenon which arises and which passes away.

... stress I had during the day.

Stress does have an associated sensation with it generally manifesting as a tightness in the head (as per Banthe Vimalasiri - see What is depression?) and / or lingering discomfort around the heart (as I have heard as being taught by other teachers to be consistent with the Abhidhamma as the mind is heart based). Based on the type of the sensation craving, aversion and / or ignorance would arise.

You have to relax both body and mind. The way to do this be equanimous of the session noting its arising and passing, or simply be with these sensation for a while analysing them before returning to your normal meditation object.

When you return to your normal meditation object have a mild smile. This is something you have is Goenka's meditation instruction though this is not emphasised much but Bhante Vimalaramsi emphasizes smiling a lot in his 6Rs formula.

Also one source of stress is worry which with you can counteract through concentration. When your mind wanders away realist it and bring it back. Periodically check if the mind is with the meditation object and even if it is fix your attention back at the object of meditation. Say if you are mindful of the body scanning part by part. You are looking at one part and the mind is still with it, then redirect the mind to the part again. If your mind is sticky stay with the part. If it is very restless either move from part to part quickly, or keep redirecting your mind to the object, i.e., fix your mind on the object, in quick succession. For someone who has practiced for a while this can break into tingling or electric sensation and further pratice this will become neutral. If you are moderately restless you can try Anapana meditation but if it is very restless best is quick scans as Vitarka dominates in this pratice. For a detailed study see: Saṅkhitta Dhamma Sutta, Uddhacca,kukkuca by Piya Tan.

... I noticed having ups and downs in my meditation, probably mostly caused by the amount of sati ...

Sati is useful to reduce though proliferation and eliminate Sankhara that follows. Make it pratice you review (paccavekkhana / vīmamsa) if you are mindful at defined intervals like end of each in or out breath cycles. This will help you strengthen your mindfullness. The description of how to review is found in Knowing and See, 4th edition by Ven. Pa Auk Sayadaw p. 35 onwards though is a slightly different context.

Sometimes it might be worthwhile to try a Samatha meditation subject in these situations.

... But I am also experiencing sittings, ...

Perhaps you can try walking meditation. Be mindful of the sensations due to body part movements and sensation of touch of the dress and / or air on your legs.

... where I am just overwhelmed by the hindrances and not even able to recognize them properly. What is the best way to deal with these extreme states of mind (in meditation)?

Extreme states are associated with extreme feeling. E.g. you feel extremely sleepy or restless. Be mindful of the feelings. If you want to learn / analyse how feelings are associated with the Hindrances in more detail, look at the Mental Factors corresponding to each Hindrance which is associated with each type of Mind State and the corresponding feeling of that Mind State. In short Ill Will be painful and the rest will be either neutral or pleasant but leave it upto the reader to figure this out exactly.

“Nothing is worth clinging to”

When this was said, the venerable Mahā Moggallāna said this to the Blessed One: “In what way, bhante, in brief, is a monk freed through the destruction of craving, that is, one who has reached total perfection, the total security from bondage, the total holy life, the total consummation, the highest amongst gods and humans?”

“Here, Moggallāna, the monk has learned that nothing is worth clinging to. And, Moggallāna, a monk has learned that nothing is worth clinging to, thus: he directly knows all things [he directly knows the nature of the all]. Having directly known the nature of all things, he fully understands all things.

Having fully understood all things, he knows whatever feelings there are, whether pleasant, painful or neither painful nor pleasant.

As regards to those feelings, [Section on Disillusionment and Revulsion (Nibbida) follows]

he dwells contemplating impermanence in them;

he dwells contemplating dispassion [fading away of lust] in them;

he dwells contemplating ending (of suffering) in them;

he dwells contemplating letting go (of defilements).

When he dwells contemplating impermanence in them, contemplating dispassion in them, contemplating ending in them, contemplating letting go, he does not cling to anything in the world. Not clinging, he is not agitated; being not agitated, he himself surely attains nirvana.

The above is from: Pacala Sutta on Sloth and Torpor but can be generalised to the other hindrances. A general outline of how the 5 hindrances can be eliminated is found in Nīvarana,pahana Vagga and also following 6 essays Nīvaraṇa, Kāma-c,chanda, Vyāpāda, Thīna,middha, Uddhacca,kukkuca, Vicikicchā by Piya Tan.

Now coming to when you cannot meditate. Insight meditation is to experience things as they are. When you say you can't meditate, it looks like you are trying to do something during meditation. Just relax and stay with what you experience (reality as it is) to the best extent you can. Also there are many meditation subjects. Change of subject also might help.

Also have 2 sessions of meditation per day at the end of the day and beginning of the night (evening) and end of the night and beginning of the day (morning). If this case one session would probably be more productive than the other if you have a storm in one session.

You are certainly not alone. Sounds like what you describe is a situation I have been in many times.

In order to find more balance, I would stay sitting still and try to remember that I could just be with the tension, fuzzy lack of clarity, confusion, anger, desire for the practice to go my way and whatever else arises. Usually this would lead to a better practice session.

This problem is mainly about unbalanced faculties. A good teacher can help yogis balance the faculties. A good teacher can be a wonderful help when yogis are tangled up like this.