Personal Hotspot Issue

Hi folks, I am having major issues today with being unable to connect my iPhone personal hotspot with my macbookair..

Everything was running ok yesterday before closing it down, but this morning I get something completely different.

Upon looking to connect to my laptop I noticed that I was unable to connect as before.

I clicked on Mobile Data and there was now a ''blue'' tag with Set Up Personal Hotspot..

When clicked it says ''to enable personal hotspot on this account, contact your service provider''

I did that and they say it has nothing to do with them. My account supports the package for my phone. It must be with the device.

I have been through many youtube videos but still nothing is clear or solving the issue.

CAn anyone offer assistance or advice please, thanks.

MJ