No Logon Screen With Black Screen And Mouse?

yesterday when i was making log out from my computer, there is no log out screen!! just black screen and mouse cursor, and when i did restart again , no logon screen appears or no any thing in screen , just black screen and mouse cursor too.I was tried every thing and no difference :safe modestartup repairrestore to some point (i dont have a point)upgrade windows or reinstall iti think the things maybe was made this poblem are :i was edited userinit.exe value from registry by deleting the comma from the end of its value. i used Windows 7 manager to make some clean and fixes some things on computer.