how do i fix a black screen

Do a reset as outlined in the iphone user guide

First Make sure the Battery of your iPhone is Charged and then press and Hold the On/Off switch (On top of your iPhone) and the Home Button (Button at the bottom of your iPhone screen). Hold both the keys simultaneously for atleast 10 to 15 seconds and you should see an Apple Logo coming up on your screen, once you see the Apple logo you can then release both On/Off switch and Home button and wait for your iPhone's Home screen.

I did that a number of times but I can still not see my Home screen. Any other suggestions.