Blocked by password

I have a dell Lenovo desktop, when I startup my computer it say drive a error, press f2 to continue or f1 to bios, when I press f2 to continue it starts up and come s to password window, when I put in the correct password it says password incorrect, and if I continue doing that it just stays on that window. I don't have a reset disk or reset key, how can I fix this problem.