Ok, in your situation, which by the way I do not support because I am a gray hat, you want to startup the admin account using safe mode. When you see the boot up logo of your computer, just hit f8 or another f button that gives you your startup options. select safemode. type in administrator and hit enter. this should boot you with full administrative properties unless your school has changed the admin password, then I think that you are screwed. You would either have to use erd commander or other ISO images burned to a cd that fake the logon. just google around for those.you could also screw it up using the package i built. i will post that in a while. gotta go!
-3xistanc3