Try doing a manual signal search on your phone to see if it reports any other carriers (e.g. AT&T, Verizon, Sprint, etc) If you see other signals but not T-Mobile, then there's probably some problem with the cell sites around you. If you don't see any carriers, something is probably wrong with your phone. If you see but can't connect to a T-Mobile signal, something may be wrong with your account.
Ouch, magenta1487400! I'm sorry to read we left you hanging with no signal -- are you still having trouble connecting? I'm hoping that this was a temporary outage (never fun, but we do our best to resolve them quickly)... but if you still don't have signal, please let us know! drnewcomb2 had some great suggestions for how to determine whether the issue is outage based or provisioning based when you're not able to give us a call to find out. Is everything working out better now?
Just checking in here to see how things are going. Were you able to get signal again on your phone?