Erase Content and Settings
I'm trying to erase the content and settings on my old iPhone so that I can give it to my Dad, but it keeps telling me that my password is not valid. It is as I am logged onto iTunes as we speak...
Try signing out of your ID in Settings>iTunes & App Store. Tap your ID and sign out. Then try a forced restart. No data is lost with this procedure. Hold down on the sleep and home buttons at the same time for about 10 seconds until the Apple logo appears on the screen. Go back to the settings and sign in again.
The only caveat to this is if you use a different ID for iCloud than you use for iTunes and App purchases.
