1) Can you navigate the BIOS?
2) Does the TRACKPAD work (unhook the mouse to test)?
If you can get into the BIOS then it may be a simple software issue. In which case:
3) Burn an UBUNTU disc and boot to it (obviously use another computer to make it). Don't install, just run from the disc. If the mouse works fine here then your problem is either Windows software corruption OR an issue with the trackpad/mouse).
*If Ubuntu doesn't startup you may need to enter your BIOS and change the BOOT ORDER so the DVD drive is first before the hard drive.