HELP! boot camp won't boot!

I tried to boot up in windows as normal and theres a padlock on the screen, and a password box. None of my passwords work and i don't know why its done this? very important work saved on it that i need to get before tonight anyone know how? i need to use a programme on that side to open it

 

i cant do a screenshot, but once i boot up, i hold alt, choose the windows partition, then it normally booted up, instead its a grey screen with a padlock and a box for a password or something underneath it