Microsoft Windows XP DELL Inspiron E1405 Password Reset

Ok, this is my first time on here, so here's my first question: My computer is giving me password problems. I know the password, but something happened. The system gave out when a friend of mine (he's not my friend anymore) was changing my password repeatedly. I need help on getting it back to normal. Can someone please help me with it? I am completely locked out of my computer. If no one can help, I'll have to resort to downloading linux instead. Thank you for reading this question.