Hey, first thing i'd like to say: Welcome to the FG forum
Maybe a look into the HPL log could help us and define the problem. But the only thing i could suggest you would be to try going to your game, right click it and go to: Properties>Local files> Verify integrity of game cache
If something is wrong with your files, this will help to make it clear and fix it. If it wont work show us the HPL log in ... i think Documents>Amnesia>Hpl
But well you should try verifying and/or reinstalling as i said above.