@KalumWhyte There are mod-related ways to cheat progress onto your sim, but without mods, no, you can't restore what was lost. It sounds like the travel transition failed, which is not uncommmon, and specifically that it failed to reconcile your sim's new progress with the old version that existed before they traveled to University. So the new data is gone from this save.
If the game's automatic backup is still intact, you could try loading that, but it sounds like it might not be. Still, you can try. Go into Documents > Electronic Arts > The Sims 3 > Saves, and look for a folder with your save name and a .backup extension. Rename it and delete the .backup part, and the save will be available to load from the Main Menu.
Having said that, it sounds like this particular save has enough issues that it might be best to start fresh. I don't know what your position on mods is in general, but for Sims 3, the best ones clean up a lot of junk data before it can corrupt your save, and also fix bugs and glitches that were never officially patched. I'd strongly recommend NRaas ErrorTrap, Overwatch, MasterController, Register, and Traveler; you can find more information here:
Without mods, it's inevitable that you'll run into some problems, although perhaps only ones that can be worked around without too much pain. It really varies from one player to another. I can give suggestions for how to do so, but it really is easier to install the mods that do the work for you, and have a longer reach than anything from the player side.
