Manual Cellular Selection disappeared

My phone is unlocked and my carrier is t-mobile. For a while now, I haven’t been able to use a single byte of data on the phone because the bars on the corner of the screen won’t show. I have an iPhone 6 and yesterday the data was working but then my phone died because of how long i was using it but when I charged it and turned it on, the data bars disappeared and when I went to Settings> Cellular and checked to see if the Network Service tab/option was there for me to automatically select my network or manually select it, I see that the tab was gone and I can only call with wi-fi and it’s annoying me because I paid for the service and I cannot even use it.