IPhone white screen problem?

IPhone 4, AT&T, 16GB. Whenever I click the home button, white screen. Connected to iTunes, said unable to connect at this time, try again later. Please help! Replacements aren't cheap!

Added (1). Lock button is destroyed. Got it used.Am I SOL?

DFU MOde Shift + Restore or Use TInyUmbrella to kick it out of recovery mode