Hi. Possible solutions.
- Check for update: Go to Settings > swipe to applications > store > check for updates.
- Restart your phone: Turn off your versed, remove the battery, remove SIM card, wait 20 seconds, put back SIM card and battery and turn it on.
- Switch to 2G: Go to Settings > Mobile + SIM, Touch "Highest connection speed" and switch it to 2G and then restart your windows phone.
- Manually select network: Go to Settings > mobile + SIM > SIM settings > Network selection > Search for networks > wait for the searching process and select your network service provider or other network to rom from.
You will kindly reply below for further assistance.