restore deleted Registry Key (keyboard/Mouse)

Hi,

I was sorting out some problem when I accidently deleted a Registry Key (HKLM). Now when I rebooted my pc after this, It has booted up nicely upto the Windows username and Password Screen. However, It wont let me use my keyboard and mouse…! My keyboard and Mouse has gone DEAD..!! 🙁 It seems I have Deleted a Registry Key related to Keyboard and Mouse..!!! I could not shutdown windows so I just have to power it off and restarted it but of no help..!!
it seems “System Restore” could help but without using my keyboard and mouse..how could “system restore” work..?? I am on Windows Vista Home Basic – got only Vista Re-installation CD from Dell – Can anybody help.?