hp omnibook xe3 gf

i know someone out there must know how to remove the password block at startup where it keeps you from even going into bios or trying to boot from floppy disk. my nephew got it at a yard sale so no bill of sale so hp wont help.he had it working then he did something an had to reboot an now it ask for the pass word before you can finish booting up. please help if you can. ive tried all the diffrent ways to clear cosmos. nothing worked. i know you have to hold down right keys to make it boot to where you can change the password the problem is which keys