Can't launch game anymore

[RagingPotatoooo]

* please note that I am french and it is possible that I make grammar mistakes*

Hello! I bought AAMFP and i played it for about 1hour and a half, saved my game and quit. About 3-4 hours later I come back to play it but the game won't launch anymore. I open up the steam menu, click on ''play'' and then the launch thing shows up for a sec and it just disapears. Also, the game stop to load as I can see the word Synchronisation next to AAMFP in my steam Library. I looked on the forums, check my graphic card, redownloaded the game few times, restarting my computer, ... nothing works. I also have a Windows XP 64 bits system, if it can helps.