I accidentally happened to shift+delete some of .dll fles and few more windows files ...?

I have deleted them using unlocker and my computer was rebooted after that. Now i am not able to do anything in my system , a black screen appears soon after i enter my personal account. Does anyone here know how to restore those files using boot menu or something? Right now I am not able to over write my OS as I don't have an OS cd with me