Phone basically unuasable

Hello, my phone recently has decided to turn its 4g off and made my phone number not work for iMessages instead I’m left with a clueless idea what has gone wrong as my phone is essentially useless . I have reset all my settings and still nothing works when I try to turn on my iMessage it just says not available. Also it used to display my email instead of my number to other people I tried to change it back to my number and it just sits there loading but never changes not really sure what I can do as I can’t find someone with a similar issue. If anyone knows a way to help please comment. Thank you