I'm sorry to hear that. Thank you for trying it and letting us know how it went.
Thanks for bringing PRP to my attention, I didn't know about it before. I don't think it would do much for the oval and round windows, like you're describing. Silverstein reinforces them, but hyperacusis isn't caused by weak RW/OW membranes, I'm pretty sure it would do nothing on that front. I also think it would be unlikely to help the stapes.
However, I AM really curious about it potentially helping middle ear muscles. If Noreña's acoustic shock model is correct, than a chronically weak tensor tympani (or stapedius) might contribute to both pain and susceptibility to setbacks. It's like injuring one of your tendons; even after they heal, they remain forever weakened and sensitive to further insults. I've done some reading and it seems PRP really helps some people with joint and tendon pain. Might it help hyperacusis too? Obviously none of this has been proven conclusively, but nothing yet has for hyperacusis. I'd try in in a heartbeat if I could find someone to do it.