Death Screen will not allow me to respawn ( Toggling Fullscreen doesn't fix it )

Whenever I click respawn the button turns dark grey and then goes back to light gray, I've went to many websites and they all say press F11 ( Toggle Fullscreen ) and click respawn. It doesn't work.
I was messing around with attribute modifiers that give my player -20 health and wither effects, which may have caused it.
Note that I am using a resource pack in this world and I have tried my best to do something with MC-EDIT 2.