I would try manually restarting the phone. If that fails, check your sound settings and make sure that your ringtone wasn't somehow changed to "No Ring." I think this has been a recurring problem for some users when they updated, but I don't think anyone's actually found a way to fix it yet.
Oh my! Sorry to hear about your issues with the device after the software update. I definitely want to get this issue resolved for you. Please try removing the back cover, battery and the sim card for about one minute. If this does not resolve your issue, we would need to complete a hard reset. http://bit.ly/swCYZF.
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