Sorry but that previous answer just won't work. If you think about it, if passwords were that easy to negate then there would be no point in using them. I am afraid that it isn't: "to (too?) technical to explain", it's nonsense. No PC hardware password can be reset like that and if it is the Windows password (more likely) then words fail me.
Assuming that the PC is running Windows, take it to a local Computer shop with ID and proof of ownership and they will reset the password for you.
I could explain how to do it but I have no intention of doing so (and I hope that no one else with either), not because it is too technical but because, in my opinion, to do so on an open forum so would be recipe for even more stolen PCs.
T
September 2011