What could be the cause of my sudden transmission problem?

I was rear-ended about a week ago. My car was hit very hard by a large SUV, and the visible damage is a lot. Trunk, bumper assembly, both rear panels. Yesterday I got up to go to work and my check engine light was on (this has never happened before), and when I went to drive, my transmission would not shift gears. It just sent the RPMs sky high as I went faster, so I drove it at about 20 MPH to work. No previous transmission issues, not even the hint of them. The only other factor is that my boyfriend (who knows little about cars) was checking the fuses the night before as my dashboard lights went out. He found the faulty fuse, and replaced it, and the light work fine now. Is it possible that the drive train was damaged in the collision and didn't show any signs for a week, or could my BF have damaged something by pulling fuses? HELP! I need to know if the insurance should cover, or if it could be a simple fix in the fuse box.
(note: the car went into drive just fine, and had no problems reversing, it just never shifted while I was accelerating)