My T-Mobile data isn’t working

You need to install a TCO/IP PING diagnostic app and run a PING test to 8.8.8.8 to see if data is working at all. If not, you should check to make sure that data is both turned on in the phone and provisioned in the switch (your account settings). I've recently heard of another person whose account spontaneously lost provision for data and it was eventually tracked to a setting deep down in the account provisions. Something Tech Support had to find. Probably the hardest thing was getting past 1st level CSRs to get to Tech Support.