deleted magic mouse driver! how do i get it back?

I need help. My mouse has been sluggish for a while now and it has been driving me bonkers. So I decided to hop on some forums today and try some stuff out that I haven't tried before. I came across a post that I decided to try: here were the instructions i followed

Move these 2 files:

AppleMultitouchDriver.kext and AppleBluetoothMultitouch.kext

to the Desktop, then delete them from the Extensions folder.

Restart Computer.

Test, and move files back to Library/extensions folder

the idea behind this: Removing them shows that the cursor speeds up, but you lose the ability to scroll. Replacing them slows down your cursor again, but you gain scrolling ability. It was just an experiment to show that it's not the mouse, it's the drivers.

So I did all of that, but when I moved the files back to the extensions folder I got an error for one of them, I tried it a few more times and it didn't give me an error, but i still don't have my scroll functionality. Funny thing is, my mouse does move faster now, and it doesn't lag at all. I just lost the ability to scroll because i deleted those two files. I'm wondering if one of those drivers were corrupt anyways and that was my problem, but how do i get it back? I've tried searching for places to download the driver but I'm at a loss now. My next step is a genius bar appointment, but I've got a mac pro and it's just so dang heavy, I thought I would try this first.

any ideas?