ayoub12 you should use source control next time, like GIT, Perforce or Subversion on a server that is not your working PC. I personally use github.com for my projects and a Perforce Server with raid at home for my raw art assets.
Any progress can get lost at any time otherwise for thousands of reasons.
Have you checked your Recycle Bin on the Desktop? Maybe you deleted the project by accident or someone else did.
If you really managed to loose all your work from three month, for whatever reason, you’ve just spend three month to learn that source control is important. Sounds bad but that’s how it is =(