I don't think that the phone has healed itself. It could be that the phone received a knock and this re-connected some component internally. For example, my Dad's amplifier stopped working, through trying to fix the problem he noticed that when it was lifted from the centre of the unit it started working again. therefore it is now supported from the centre and works fine (presumably this slight stress change in the case allows some contact inside to be re-connected.
Also the temperature of a device can start or stop it working due to expansion and contraction!
Hope this helps some - you lucky sod
