I had a Personal Hotspot item in my General settings, it disappeared

I've had a Hotspot for years...I switched from Verizon to AT&T...

3 weeks ago, I got a message that I was getting close to my Hotspot allowance, then they would throttle my speed.

The next day my Hotspot item under General Settings disappeared.

How do I get my Hotspot back on my Ipad Air