jonney, and julien, the first recommended way to troubleshoot an issue like no internet, is to pull the battery (while the BB is powerred on) and reboot the device. You could first go to "Manage Connections", > Mobile Network > uncheck that to OFF, wait and recheck it to on . Sometimes that will regain the signal.
When you say you have no internet, do you mean no data at all? What is your signal reading?