A hard reset will reset your N73 phone to the point it was when you got it.  I keyed in *#7370# and it prompted me “restore factory settings to default?”  I clicked yes.  It then asked me for my “lock code”… I keyed in 12345 and clicked OK.  The phone restarted and asked me to select my current city, current time, and current date.  It then asked me if I wanted to do the tutorial which I skipped.  Everything seemed to work okay.  Prior to doing this hard reset I had upgraded my N73 firmware during March 2010.

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