Did you do a hard reboot - pulling the battery for a minute while the BlackBerry was running?
You can re-register with the network via the Host Routing Table in Options > Advanced Options > Host Routing Table.
Make sure you're not still trying to use WiFi after leaving a Hotspot area:
KB20291-Unable to receive data over the wireless network after leaving a Wi-Fi hotspot
Re-validate your email accounts:
KB13137-How to re-validate your Windows Live Hotmail, MSN, and Bell Sympatico email integrations