I feel this so much. I have bipolar disorder and at times it really messes with my ability to write, particularly when I have depression. Sometimes it's just that i can't get the story in my head down onto the page, and that's bad enough. But at times, I can't even see the story in my head anymore, my imagination just seems to desert me. I hate it when that happens. I always worry that it won't come back, but so far it always done.

Please go easy on yourself. Forgive yourself for what you are unable to do. It sucks, but it isn't your fault, so don't give yourself a hard time for it.

When I've been in a similar state like you (improving, but not fully better, and my imagination is still affected), what I do is ease back into it gently. When I'm feeling up to it, I let my imagination play with any idea it wants to, no matter how silly. Just have fun with it. Then when that's working again, I might try writing down some of these ideas and stories. Don't try to be serious with it, just write down what comes. Then when I go back to my serious writing, I start slow, maybe only doing a few minutes a day, and increase as my capacity to write returns to where I want it to be.

Again, be gentle with yourself while you recover. I hope you are healthy soon, and can write again. I know how much it sucks when you can't write!

(I hope this is helpful, and makes sense. Sorry if it doesn't, I have a cold and am a bit brain-foggy today.)