Upvote:4
First, OPT has a requirement that you cannot have more than 90 cumulative days of not being employed in the U.S. So if you stopped working in December, by April you will already have more than 90 cumulative days of unemployment, and you will have violated the terms of your OPT and you won't have OPT anymore.
Even if someone has not violated the terms of their OPT, immigrations officers will generally not let someone back in on OPT unless they have either 1) paystubs or other documents showing continuing employment with an existing employer in the U.S., or 2) an offer letter for a new upcoming employment in the U.S. You don't have either, so even if your OPT was still valid, you would probably still not get in.
Yes, your F1 visa is valid. But the visa is useless unless you have a student program or OPT to go into, which you won't have in April.
You should get a B2 visa for visiting friends.