go blank
1. To unexpectedly forget something. Can you remind me of your name? I'm so sorry, but I've gone completely blank right now!
2. To lose consciousness. My blood sugar dropped so low during the meeting that I went blank and woke up on the floor.
3. To no longer show a picture, as of a TV or computer screen. If the TV goes blank again, just smack it a few times—that should help.