Are you talking about the moment you power it up a password field apears? In that case, from the bios you must of entered a password while you or someone else was messing around and it now requires that password.
There are ways around it. A simple google search will help you, for example (example only) type "PC2000 Bios Password Recovery" And useally a keygen type program is needed. You will find it, download it, then it will ask for the serial on the laptop, from there it will generate you the "master override" code which you type in and get into your bios to deactive/change the password.