Put the summary of the bug you're having here

What I expected to happen was...:
I expected the game to go into fullscreen mode like normal.

What actually happened was...:
The screen went black and now when I try to open minecraft the screen is still black.

Steps to Reproduce:
1. Go into minecraft
2. click play
3. click options in title screen
4. click video settings
5. click fullscreen
6. the screen should go black, then do command Q
7. open minecraft again
8. click play
9. It should seem normal for a second, then go black. (this is my bug)