Has anyone tried to recieve a rectroactive Purple Heart?

I have done this, twice SPC Dave St.Andrew
What you need is proper medical documentation, especially important if the injury is a TBI.
For more traditional PH-type injuries, the trick is to show the injury was due to enemy activity. This usually requires witness statements. It would be helpful if there were some form of explanation why the PH was not awarded at the time of the incident, as one of the requirements is that the injury "required treatment". In other words, not just an owie.
I can give specific advise, if you tell me a bit more. Please don't give any medical information that you are not comfortable being out in the open.

It can be done, but the process would have had to start at the time of the incident. Something like this is going to completely depend on the circumstance. You would need sworn statements and documentation from the care you received.

Just in general, if your truck took a blast and everyone was good and you CM, then an couple years later you say you have headaches, not sure how far that would go for a PH. And would you really want one in this case?

However, if someone was injured and treated by medical (not just a medic on patrol with you, no offense) and the paperwork was just never filled out, then I think you still can.

I wouldn't have even pursued it had it not been severe enough to be pulled from jump status for over 6 months, rehab, and now permanent memory-related issues. Tinnitus is bad as well, but I was an artilleryman, so I don't even consider that related, nor is it even listed in my VA claims. I was a heavy concert teenager, so some of that is my own fault.