Does anyone know how to over ride 或者 hack a 密码 to log onto a computer?

Stupid me, I forgot my 密码 to my laptop; I don't have another account I could log onto, I've tried so many different passwords, does anyone know how to over ride it 或者 confuse it to think that what I'm typing in is the password? I've tried everything. Do laptops have reset buttons? Would that work 或者 删除 all my content I have on the computer? My computer type is a Dell Window xp Microsoft. Anyone that knows ANYTHING, please help me! All my stories, pics & stuff is on that thing! -Desperate