MacBook Pro turns on, but screen does not

When I restart my MacBook Pro (Retina, mid-2012, 15 inch), I hear the Apple startup sound, and keyboard lights up and I can press the volume buttons and hear sound, but the screen stays black. It seems to be turning on and starting up fine, only the screen doesn't turn on. If I close the lid and wait a few minutes and open it, then it works.

Also, sometimes when waking it up from sleep mode, when I open the lid, the screen is all black. Again, if I close the lid and wait a few minutes and open it again, the screen turns on.

Also, for the past few weeks, every couple of days it will just freeze, the screen will go completely white or turn off, and is completely unresponsive. Don't know if this problem is related to the screen not turning on.