When the game locked up on you and you restarted the computer, your saved game probably got corrupted.
This likely means you are going to have to start over from the beginning, sadly.
But here's what I would try:
1) Go into your My Documents folder > Disney Interactive Studios > Tron Evolution > SaveData > SomeLongNumber
2) Make a copy of the CHECKPT file in that folder, and put it somewhere else. Then delete the CHECKPT file in the Save folder.
3) Try running the game and see if it still crashes.
If it starts up okay, quit the game and then copy the CHECKPT file back into the Save folder. If the game crashes again, the save file is corrupt so you'll have to delete it once more.
To prevent this from happening in the future, use GameSave Manager
to back up your save every time you quit the game.