W580i "No network coverage" need help

I have a W580i its about a year old and it worked fine until I loaned to to my daughter she brought it back and the thing says "No network coverage" on it.I asked if she dropped it she said no then I might have.Would flashing with new firmware or ATT custom pack help this?Everything works great on the phone it just says no Network coverage.Any help would be appreciated....P.S..I did have to replace the screen once, but that was 2 or 3 weeks before this problem happened.

Your cell phone may be broken by the hardware, I suggest you to repair under the

You problem is hardware .
This phone have coaxial cable who conect PCBoard and Antenna
-First check this.

check u r antenna connections/connectors..

did u get emergency call signal?? if yes Sim fault

hope dis helps..