Do you get anything in the bottom left corner when you click on 'Get Messages'? If you add the 'Get Messages' button in View/Toolbars/Customise, does this have the same effect? Do you have Messages to be automatically retrieved )Hamburger Icon/Account Settings/Server Settings/Check for new messages every AND Automatically download...) ?

I already have Get Messages in my toolbar. When I click on it, there's no response in the bottom left corner or anywhere. My server settings have Check for new messages every 10 minutes. I don't see any setting for Automatically download.

I keep thinking tjhis might be related tp a mismatch in some login or password with my server account. I had this problem before and somehow I got it working again but Thunderbird then always had me enter the login and password on start-up. Then, a week ago it didn't do that but the e-mails also stopped arriving.

This is IMAP or POP?

The main problem at the root of not receiving emails is Third Party Anti-Virus software. I'd suggest that, if you have any installed (especially Norton or Bitdefender), you switch off Email protection temporarily and see if it's magically resolved.

You could start Windows in Safe Mode with Networking but that would be pretty much the same reason for switching off Email Protection.

Apart from that, I don't have a solution for you. Please respond so that this question goes back into the list of problems that need resolving.