If it asks for a password when trying to enter the BIOS it might be a supervisor password (or hard drive password) set in the BIOS that is required.
If the password is when logging in as a user in Windows, it is a windows user password.
Anyways, without more precise information this is my recommendation. Try Hiren's Boot CD. In my experience it can crack trough most password on different levels of the system.
Just be careful! Only use software included on the disk that you know! There is potential to really destroy your system with this CD if used carelessly.
https://www.hiren.info/pages/bootcd