Iphone is not responding

Basically I needed to erase all content from my 3GS so I went ahead and tapped Erase contend and settings from the settings menu. The phone restarted but it didn't make it all the way through. Now all I can see is its normal booting apple logo on a black background. Then the loading wheel starts spinning but really really slow. After a few minutes the phone restarts again and it goes all over again. Resetting (home+on/off) does restart the phone but then it's still doing the spinning and self-restarting again in a few minutes. Connecting to a computer doesn't make any difference.
os 3.0
idk what to do