Desktop version of Microsoft Excel suddenly Not Available

I'm suddenly no longer able to access the desktop version of Microsoft Excel. I am a subscriber to Microsoft 365 for work and I also have a Family subscription to MS Office, which allows me access to the desktop versions of the Excel, Word and Powerpoint apps. However, I've suddenly been disallowed from accessing desktop version of the app. When I open the app and go to Recent Files .. they are all greyed out. The app simply stops working. File>Preferences not available to me either .. its greyed out too. I've updated to the latest version of MacOS and Excel. I have no issues using the online version of Excel, it just has less functionality and I much prefer the desktop version. I've re-installed Excel.. I'm logged in to both work and personal profiles for my Microsoft accounts. I'm at a loss. Any guidance or suggestions ... I'd be most grateful. Thanks !