Reformatting?

I have many Dell computers.  I have always used the ctrl F11 at reboot to do a complete restore.  I bought my twins computers last year for their birthday.  And put passwords on them.  Well I have forgotten the password.  Fortunatly I was able to reformat the one back to the original settings but the other will not do the ctrl F11 restore.  Can someone please help me.  If you don't my teen is going to reak havock on me forever.

Thanks a desperate mother!