So my son was dimming his screen and then he locked his screen with a password. But the screen is dimmed so much it is black and cannot tell when to put in the code? Help
The screen dim controls on the side of the device won't dim the display that much. It might be a backlight failure and the device could need a repair.
You can take the device into a room with a table lamp and usually shine the light on the side to see enough to operate a screen even with the backlight totally failed.
You can unlock the device by connecting it to the computer that it normally syncs to in some cases as well.
With iOS 7 you can open Control Center to adjust the brightness.
Turn the display on using the lock button. If you're not sure if the display is on, press the lock button, wait about 30 seconds, then press the lock button again.
Swipe up from the home button to the top of the display.
Swipe right on the display starting 4 cm from the bottom of the display (4.8 if you have AirPlay) and 0.9 cm from the left side. This will increase the brightness.