kristyhawkins, First thing I would try is a reset. Problem could be that all your data will be erased, except data stored on the microSD card. From the main home screen, tap menu
Tap Settings, then Privacy
tap Factory data reset
Tap Reset phone
Enter your password, then tap Yes to confirm
Or you can do this for another way of resetting.
Turn the power off. Pull the battery out and reinsert it
Hold the Volume Down button
Press and release the Power button
Select Clear Storage by pressing the Volume Down button
Press and release the Power button
Now confirm your decision: Volume Up for YES and Volume Down for NO
If a restore did not make a difference, It is time to open your phone and check for any disconnected or broken connectors. If all of those are okay, the problem will be a broken LCD. The assembly is available at places [http://www.xphoneparts.com/item-search.html?nkw=Samsung%20Epic%204G|like this.] Hope this helps, good luck.