Phone Ceased Sending Text Messages

I have an iPhone 11 why weren't the texts I was sending being received I'm not great with phone/computer stuff. I called T-Mobile last month they said nothing was wrong had me reset it and said they ran diagnostics. I had already reset it multiple times I had a job that paid enough to support myself and cover my moms rent, prescriptions, groceries that Soc sec wasn't enough for. That job required me to text my boss everyday to find out what job site he text me off due to weather I texted every day on group texts n just him nothing back no replies they didn't get my messages I drove 2 hours to the corporate office after I received a paycheck in the mail n a letter of termination for not contacting anyone. So if anyone knows how to fix this please let me know this issue has cost me $1,200 a week in pay it's winter replacing my job is impossible right now