Can't Stop Reliving My Car Accident

First recommendation I'd have is therapy (it has completely transformed my relationship and vulneraibilty with my trauma). If that's inaccessible to you right now, I would definitely suggest looking up "grounding exercises." Things that bring you back to the present when you get caught in a flashback. PTSD is our mind thinking that something that happened in the past is happening to us again right now in this moment. By doing grounding exercises, you're essentially telling your brain, "I know we're scared right now; but in this very moment we are safe, that moment is not this moment, and there is nothing to protect ourselves from." One thing to note is that they tend to take a lot of practice. Practice them when you're not triggered, when you're relaxed and safe. Then when you do get triggered, you're used to it and it also brings you back to moments where you feel safe and relaxed. I really hope this helps!