1. do a windows file search for all *.mb and *.ma
2. search the project folder location
3. search the autosave folder in the project location (if you have turned this on). If you have not turned this on I highly recommend you do. I set mine for every 5 minutes and keep the last 12 saves (so the last hour of my work in 5 minute intervals).
4. look in the maya crashed file folder. (user dir) / AppData / local / temp. Depending on the version of windows the user dir will be in documents and settings, or the users folder. If you are using mac I don't know where this folder is. The crash files will have the names (user name).(date).(time).ma (ex ram.20120308.0523.ma). Just look for the one with a date and time close to the last time you had the file open. This will only be there if maya crashed and could save the data. You may be able to get some version back assuming you crashed at all while working on your project.
This is a hidden folder so you'll have to make it visible in the explorer properties.
If you are on a school community system then someone could have deleted your project folder or changed the path that maya looks for projects so maya could be looking in the wrong place and therefore cannot find your files.
For the former, you are boned, for the latter you will have to do some hunting.
Just for a note Maya does not under any circumstances just delete an open file on crashing. The only way it could have gone missing is if it was physically deleted by someone, or moved.
Good luck.
"If I have seen further it is by standing on the shoulders of giants." Sir Isaac Newton, 1675
Last edited by ctbram; 09-03-2012 at 10:57 PM.