When ever i text on my Phone it says retry and i retry but it keeps saying that ,and wont let me

and when i call some body, i cant. it is like the phone is not letting me call, and i have unlimited minutes

is there a problem, do i need to change some settings? if i do, can you like help me thank you, and tell me what to change.
and if there is anything else i need to know to prevent this from happening again, i would like to know
Thank You. Plz i need to know

Plz Plz Answer Plz Plz

Best answer will go to you