After upgrading to Lollipop from 4.4.4, mobile data doesn't work. I have tried all the solutions listed in various forums including, 1. Reboot 2. Reboot after re-inserting the sim card. 3. Manually add the APN (Got the settings from the service provider) 4. Toggle between the Preferred Network type (2G and 3G)
I have only one usable sim slot, and so cannot use sim slot-1. I have heard it worked for a few guys after putting the sim in the other slot, but unfortunately I cannot try that out.