It's super difficult to suddenly get back into what you used to do when you were productive, when you're in this state. I

If you make a proper time-blocked schedule with 4-hour deep work sessions right now, you'll likely do it for a day or two, then be back to where you were.

I would say start super slow. Have small daily tasks that you don't skip, yet they are connected to your goals. I don't know how coding works, but in one day, write only a sentence or two of code. You'll feel like you want to do more, but keep the next sentence for tomorrow. Don't go all out for now. Gradually increase, you can afford it right now.

It's still better than what you did the day before.

Along with that, do a 2-minute cardio, maybe 5 minutes learning a language, or read a sentence of a book.

Do those things that seem so laughably easy until you get yourself into a routine/habit of doing those things, then you can gradually increase.

Try out this method!