Preperation to editing - problems

PROBLEMS! Jeez!...

The first thing after rendering I realised that there is no sound at all. I have seen some people using their normal sound and just adding effects, which looks quite cool and more realistic. My recorded video has no sound at all. I really would be surpriced if I'll lose marks, because of lack of sound effects. I also must admit that watching video without sound is extremel BORING!

Later on, at some reason my disk kept ejecting itself automatically. I have lost quite a lot of work because of that, and also it took some time to sucessfully transfer my folder to another disk. So, even more time wasted...!