Help Desk Sent Me Here...Help!

I'm getting the msg in a ribbon at the top of my excel files as follows: COULDN'T VERIFY SUBSCRIPTION Excel couldn't verify your Microsoft 365 subscription. Please make sure that you're connected to the Internet. ( I am ). we've rebooted several times, uninstalled, reinstalled etc. I can open all my excel files, but can't edit or save them. All dropdowns are "grayed" out. Microsoft Help Desk sent me here.