Help with Vegas 8.0 rendering

[TheGT4sm]

Well... I got a little problem in Sony Vegas... not a big problem, but a little problem I want to solve.
I usually had alot of stuff like MP4, and much fancy stuff.
but SUDDENLY alot of things dissapeared... now I have a few things like: WMV, AVI, WAV and stuff you know...

So my question is: Is there a way to get those things back? because I really want it so much...