Exporting screwed up my entire project I need help

Help!!!! I was working on a major project and when I went to export it said there was a failure and a couple things happend:

1. I lost one of my 3 exports even though the second one failed and I never got anything???

2. When I went back into editing mode I had lost ALL audio and picture ability, and everything you watch is replaced by a red screen and white exclimation point. 

I have been working on this for weeks and am scared I'll have to start over, does anyone know how to reverse this and go back?