I tried to do a restore (was having issues).
Now when the phone turns on, after a minute of the Apple logo, I just get the logo with a spinning wheel, and a double-vibrate.
It won't go past this.
FIrst, is it a V1 or 3G? and are you inside of your first year warranty? Were you Jailbroken? What version firmware.
Second, Try this: Power off the phone. Launch iTunes. Connect the phone and wait till iTune sees it. Connecting your phone should automatically turn it on. ( if it doesn't see it, see below)
If iTunes sees your phone, do a search for IPSW files on your PC, write down the name of the newest one and then delete it. If it is the latest version of firmware, 2.1, then click restore in iTunes and it will re-download the firmware and install. if it was older, you need to search the web for it, donwload it to where the original file was, and then- while holding down the shift key, click restore, browse to the ipsw file and select the new one. Hopefully that will solve your problem.
If iTunes does NOT see your phone, you will need to set the phone in DFU mode and restore from there. Search for DFU mode on here for the exact instructions. Its been a while for me, so I cant tell you how to do it.