What do I do if I have no cellular data and it won’t work?

To refresh your wireless connections, aside from restarting your phone, you can simply enable then disable the Airplane mode.

If this did not fix this, try following the instructions on this Apple Support page: If you see No Service or Searching on your iPhone or iPad - Apple Support

Rashed2000 Said:

"What do I do if I have no cellular data and it won’t work?: What do I do if I get no cellular data on my iPhone"

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Whom to Contact:

Contact your Carrier, as they are the one who provide you with the service of Cellular.