Computer locked upon hard drive how to bypass

Well here's the run down when i start my one of the computers that i bought off someone, the hard drive is locked to i have enter a 8 letter password in order to get in, but i cant start f2 being boot option n when i enter the password is says invalid password, i managed to get in Windows 7 setup but thats where im stuck and there is no C: i cant do anything about it
Please help
specs:
Gateway running windows 7 starter LT2103h
thank you

Best would be to ask the person from whom you bought the PC what the story is. It sounds like the drive is encrypted.