Trackpad not working

My trackpad isn't working, and I'm not sure why, s I was wondering if someone could help me with this. I had plugged in an external hard drive via USB, to see if it was working or not. I knew it was bootable, so I restarted the MacBook, held down the option key, selected the external drive, and found out that it was not working as I suspected. As it was stuck on the gray Apple logo screen, I had to hold down the power button to restart. I went ahead with booting via my internal drive (which was working perfectly fine, by the way) and at the login screen, discovered that the trackpad wasn't working. I'm completely reliant on the trackpad and don't have a mouse to use, so help is needed!

 

Sort of. I get to the login screen, and can't select my username because the mouse is stuck in the corner and won't move. Everything looks normal, though, other than that.

 

No idea. I can't type in anything since I can't navigate the arrow away from the top corner. . But, I did try hitting the caps lock key, and it won't light up, if that means anything! This all started when I tried to boot from the faulty drive...that must have something to do with it, i'm thinking...

 

Ooh, two more things - resetting the PRAM didn't fix it, and I don't think it's a USB issue because my two external USB ports are still working...but what do I know?

 

Nope, still isn't working! And I even tried plugging in a USB Mighty Mouse and Apple keyboard, and that didn't work either. The mouse lit up on the bottom, though, so I know it was getting powered. This is so weird!

 

Yeahhh, I was afraid an archive & install would be the next step! Guess this means I'll be making a trip into the Apple Store tomorrow, as my install disc is currently MIA. Should be fun in the blizzard!

 

Yup, a quick archive & install at the Apple store fixed it. (I really do need to find my install cd!! ) Thanks everyone for all of your help!!