Phone help...please

Hey guys,

So i have an HTC Inspire android phone that i have had for about 2 years. I have AT&T. Today i have had problems with service. I HAVE service for my phone but its been saying no service for the last 4 hours and i cant get the X to go away. I heard factory resetting is helpful but i read online that some people had problems with that.

Any adivce on what to do? Tips, suggestions, or experiences would be great!

Thanks in advance:)