iphone 5 cant connect to 3g anymore

I updated my iphone 5 to ios6.1 almost two weeks ago, and 3 days ago out of nowhere my 3g connection was gone and nothing that I tried seems to help:

switching wifi on/off

switching 3g on/off

back up restore

full restore as new device

setting up apn settings

and another strange thing is that a friend was not able to call me from his cellphone because my network was gone and I am not able to call him or other numbers but my mother was able to call me from her work and from her cellphone.

whenever I look up 3g problems ios 6 everything I read is about the 6.1.1 update for the 4s but I hoped that if other people have the same problem on the iphone 5 that apple would look into it asap