my screen is suddenly green

try tapping your home button 3 times very quickly

Also, try to do a hard reset. This is done by holding the Sleep/Wake button and the Home key down simultaneously until the Apple logo appears.

What was happening/ what task where you performing with the iPhone before the screen turned green?

Have you downloaded any new apps recently?

THANK YOU! OMG DROVE ME NUTSO home button 3 quik times WORKS. U Rock!!!