Photo Booth Crash every time I launch it..help!

Actually, I am a beginner of Mac. I got my air a week ago, and 3 or 4 days after, I find out that the Photo Booth could not work.....

It CRASHs every time i tried to use it. At the same time, my webcam works with Facetime and quicktime player.

Thus I think the problem must be in the software itself...

Utill Now I have tried several methods to solve, but all of them fail to work

Also I can't find the file "com.apple.photobooth.plist" accroding to some solution (delete the preference file)

What should I do then..?