Disabled USB

Ok I did something REALLY stupid!!!! In the midst of trying to do too many things at once on 2 computers I messed up big time and really don't see a solution to this problem but here it goes. There's a series of things that I was trying to do to improve my computer. One of them being was to upgrade my computer to its max memory 8g. I installed the memory with the idea of upgrading to 64-bit and the plan was to upgrade from my xp pro 32-bit to vista 32-bit and then to 64-bit. I thought that would have been the easiest way to make the transition without having to reinstall all my programs and settings. In the middle of installation of course the computer will have a series of shut downs and rebooting. In the first shut down and restart the computer froze. After looking at some forums of ppl having the same problem someone suggested to disable USB to ck to see if the mouse or keyboard was causing the problem. After pressing F2 and disabling the USB I thought that I would be able to put a USB to PS2 converter on my keyboard for use after start up but no connection. And so I'm stuck with no OS properly installed and no way to change any settings. PLEASE HELP!! I know some technical stuff but I'm a 3D graphics artist and as you can see not the brightest in this area. Thanks to anyone who has any suggestions in advance.

AS far as disabling something in BIOS and getting it back, set BIOS to default and save and exit.

Read in the MB manual, 'reset CMOS jumper'. Reset the CMOS jumper and default the BIOS.

ok thanks for the advice. I was able to remove the battery and put it back in but I had to partially remove my graphics card to do it and now thats not registering when i turn the computer on. I popped it out completely and then inserted it back in but no go. This is a nightmare! Should i attempt to pop out the battery again with the graphics card inserted this time around to see if that works?