My password doesnt work to open my laptop!!!!

... I cant open my hp pavillion dv6 laptop...ive set a password before but i dont know why it doesnt work anymore..when i try to open it always says "the user profile service service failed the log on,user profile cannot be loaded"!!
I dont know what will i do...im afraid to lose all my files..please help.........
tnx in advance for your help...
...pauline