how to reset my phone

Reset, is holding both home and power buttons for 10 seconds until iPhone restarts itself.

To return iPhone to Factory Settings:

Restore is connecting iPhone to iTunes on computer and selecting the Restore button of iTunes allowing iTunes to return your iPhone to Factory settings. To do this on iPhone, tap Settings App > General > Reset > Erase All Content and Settings.

iphone 3GS ? After pressing to reset on the phone stayed on the blue screen with white circle spinning for over 12 hours? is this normal?