Ok dead easy.

Sync/ back up your phone first. Unplug it from everything (make sure it's charged, obviously).

Go to Settings > General >Reset (right at the bottom). First of all try reset network settings. Enter all the bits you need to.

If that doesn't work, try the more general reset all option. It's not labelled Factory settings but that's what it is. It'll take it back to where it was when you got it out of the box.

Not to taken lightly but if you're backed up, you should be fine.

Posted By: pieman63, Jul 23, 20:25:27