Bios password

Hello, hi i got an advent 8115 boot up and ask for bios password, i entered a password and run it and then i goes to bios for to remove it.it ask me for old password and new password i entered a old password and in place of new password i just entered a enter key and then restart it again its ask me again password and i tried an enter key and my old password but its not working can u tell me what to do now