First of all, what operating system is this? Are you talking about the Windows user password or the BIOS password? (I assume the Windows one?) If that is the case, sorry but you're outta luck if you totally don't have any user account with a password you remember. It's time for a reformat.

I would first try safe mode and see if the Admin account has a password ,some time people just password the account with there name on it ,and don't even know there is a admin account in safe mode .If this is the case and you can get into safe mode go to users in control panel and create a new password to your account .

i have the same problem but when i start in safe mode it hangs after about 1-2mins. I have a guest account with no password, just for internet use and troubleshooting sort of stuff. help!!