F12 boot menu to reload Windows 7

Hello,
I own a ACER Aspire One netbook. Recently my daughter change the password to my computer and I didn't set up a guest screen to go around the back, so I'm trying to reload Windows 7 through the Boot Menu (F12 at start up). I access the setup menu (F2 at start up) to enable the Boot Menu and it won't let me change the value to "enabled". I tried everything I know to back door this problem without having to send it back to ACER! Is there anyone that can help save me some money, please?!?!?!?!?

Thanks http://img.tomshardware.com/forum/uk/icones/smilies/hel...