My laptop keeps asking for a password that I don't have what do I do?

Give it back to the person you stole it from.

Call up your friend that you bought it from and ask.

Why don't you have the password?
Password doe not just get set, it has been there all along, unless someone has changed it.
As well, what password? The BIOS, Windows?

Hit cancel and continue on.

Boot up your laptop with a dummy bios, then you will be able to log into the account, and change the password. Or an easier solution would be to simply ask your friend for the password?