FOR WINDOWS XP ONLY
Ive done this many times, and it's easy.
- First, turn off the computer. While it's loading wait for a screen to come up with "start up options" (it may be different but just press f8 when an option involving f8 comes up).
- You will now be prompted into the safe mode options. Choose reg safe mode and wait for it to boot up.
- Where the login screen is should be an account named "Administrator"(it may be different, just click on whatever account isn't usually there). Click and log in.
- You now have access to a admin person thing - now you can do anything an admin can do. You need to go to control panel and click on "user accounts" and choose a new user and name him whatever and make it an admin.
- Now restart and load in reg mode. Log in with the char you made and go to control panel-user accounts-manage and make your main account an admin if you want.
- Log out and go on to your main account and delete the other account you made.
YOU NOW HAVE ADMIN ACCESS ON YOUR COMPUTER. NOW TO UNDO IT...
Go to control panel-user accounts-manage and admin yourself. It's that easy
This might not work on all comps, but it worked on the computers of everyone I know