Files went missing when I put dvd in?

The windows live movie maker project I have been working on was perfect and ready to be burned onto a disc until a stuck in a new dvd to burn it on. Once I stuck the dvd in about half of the files on the project got a a yellow triangle "fix it" error on them. This is a huge project (over an hour of pictures/videos/with music and captions throughout) and I cannot seem to return it back to old form even though I saved it before... I tried fixing some of the items but it scrambles everything up and makes things worse.  If someone could offer me advice her I would really appreciate it because this thing has taken my whole weekends for the past 2 months and I cannot afford to lose it!!
Thanks!