Hp 6720s i have this laptop and i put a power on password, and all is working, but latter i remove it and the computer is asking me for a password and not work with the old password. Can you hellp what to do to remove the password??

This WEB site has instruction on how to remove this password.
http://h30499.www3.hp.com/t5/Notebook-HP-ProBook-EliteBook/Compaq-6720s-power-on-password/td-p/1082332

1) Turn off computer
2) Disconnect AC adapter
3) Remove battery pack, and remove the laptops keyboard
4) Disconnect RTC (Real Time Clock) battery (located underneath the keyboard, the red/white wire)
5) Leave off for fifteen minutes
6) Reconnect the RTC battery and reassemble the laptop
7) Reconnect AC adapter (DO NOT REINSERT THE MAIN LAPTOP BATTERY AT THIS TIME!)
8) Turn on the computer and enter the BIOS by pressing F10
9) Set the new BIOS password and save all settings.
10) Turn off the laptop and reinsert the battery

Hope this helps ...Lee

Laptops dont store the BIOS password like desktops meaning that even if you find the Battery the password wont be deleted since its stored on a eeprom.
best way to go is to go to compaq they will help you if you have proof of purchase

I forgot my power-on password hp6720s what is the solution?

Do you want to know about bios power-on password reset on HP 6720s?
Turn to Reset HP BIOS/Administrator Password
It shows you how to reset HP BIOS password with SpareKey, and how to reset HP administrator password with effective Windows Password Genius in just 2 minutes.

Get a video learn how to use it:
http://www.youtube.com/watch?v=-vrVcFaUATg&feature=youtu.be

Removing the RTC battery and leaving it uninstalled for 5 or more minutes causes all passwords and CMOS settings to be cleared. BIOS password can be removed by temporarily disconnecting/ removing the RTC/ CMOS (Coin-cell) battery from the motherboard. Disconnect the coin-cell battery from the system board and it will reset the BIOS to its default setting and the password would be gone.
Please Refer to Page 77 of the REPAIR MANUAL HP 6720S.
If you can't do it yourself, you may seek help from local laptop service professional.

GoodLuck!
Dont forget to appreciate the solution if I could have been of any help!
CreativeTECH

Power don the computer and try removing the BIOS battery, the rechargeable battery and the power cord for 10 min. This will erase the BIOS and re-set it to factory defaults, also clearing the BIOS password

The backdoor password for Compaq computers is "Compaq". Try entering that and it should work.

Remove accumulator too. Firstly accu then RTC battery and before this power supply. You need to put your laptop to no power for about 5-10 min

I have a compaq 6720s and I cannot remember my power on password to get into my system. Please help me. I do no know what to do.

Thanks Cherry