Strange no sound problem in cubase elements 8

Hi guys… Apologiez in advance for potentially bad grammar. I’m Norwegian. Anyways… After about a week away from “studio”, I can’t get any sound from any tracks of any of the projects saved on my PC laptop. Neither VST or audio tracks. The indicators in cubase show that there is sound, but nothing but the metronome gets trough my interface. The backup copies of the projects on my external hard drive works just fine, and I can create new projects with no problem at all. It is only the projects saved on my laptop that won’t send sound (exept metronome) trough the interface. This goes way over my head, and I’ll appreciate all help to understand the problem☺