09-04-2013 05:28 PM
Hi and Welcome to the Community!
With a strong carrier network signal (e.g., not merely WiFi), I suggest the following steps, in order, even if they seem redundant to what you have already tried (steps 1 should result in a message coming to your BB...please wait for that before proceeding to the next step):
1) Register HRT
Hopefully that will get things going again for you! If not, then you should contact your mobile service provider for formal support.
One thing to check carefully is if your mobile plan includes BIS -- there are reports from some that having BIS enabled on a BB10 data account can actually prevent the functionality of the BB10 data via the mobile network (and, since BIS is not used by BB10 anyway, having it is redundant and also more costly in some regions).