Specific project doesn't sound

I have Cubase LE AI Elements 11 and everything works fine, except ONE project file. When I open that file I can not hear anything, when I open another everything is fine. Same settings, same audio etc… and cubase says like everything is “Active” everything is just the same as the other project files, but no sound. Do you have any idea how to solve this?

Are the tracks routed to the output?

Press F4 and check your audio connections. This is usually the cause of this problem for me.