Blackscreening When I Go Fullscreen

I have reset minecraft as of 7/29/2016 and since then I was out with a friend I came back and reset my minecraft and backed up my resource packs mods and all that shizzle but when I reinstalled all my stuff back in and started minecraft just to get the folders loaded it started black screening in the middle of F11 when i press it it just black screens for a few seconds and thats annoying as it did not used to do this problem before and I keep on dieing in minigames as I need to check the time.