If you took notes it shouldn't take you very much time to reproduce the prints. Just reprint the negatives using the times and settings in your notebook.
If you put one of your spoiled prints in the easel and the matching negative in the enlarger you simply move things around until the two images line up. Dial in the aperture and time. Set up your filter and hit the button. You should be able to finish all those reprints in an afternoon's work.
Another hint: Always make a backup print. Once you have worked up a good print, it's a small matter to stick anohter sheet of paper into the easel and hit but button once more. A second print takes very little time to make and, in a situation like this, you might have been able to grab your backup and save the day.
I do agree with the rest. Make sure you fix your prints properly. Use clean fixer and rinse the prints well afterward.
In a community darkroom it's not uncommon for the fixer to exhaust quickly. If you've got four or five people developing prints, the stuff wears out in no time.
Don't be afraid to pester your teacher or lab assistant to replace the chems when they need it. If the darkroom is busy, it might be necessary to change out chemistry every half hour.
If you got stains on your prints from dead fixer, chance are other people have stained prints too.