Microsoft Products, excel, word, notes are no longer working

If you have an early version of Office for Mac 2016, you can update it at no charge. See: https://docs.microsoft.com/en-us/office365/troubleshoot/administration/office-2016-for-mac-64-bit-upgrade

If you have Office for Mac 2011 or earlier, you can either subscribe to Office 365 or you can make a one-time purchase. See: https://products.office.com/en-us/buy/compare-microsoft-office-products-for-mac?ms.officeurl=mac-compare-redir

Or the free Microsoft Office on the web: https://products.office.com/en-us/frhttps://www.libreoffice.org/

Or Google Docs: https://www.google.com/docs/about/

Other options include using the free and very good Libre Office https://www.libreoffice.org/

or Apple's Pages and Numbers

If you are thinking about giving it a try: after downloading and installing LibreOffice, right-click eg on a Wordfile, leftclick on Get info. Choose ‘Open with’ Libre Office and check: use this app for all files

If you don’t want to upgrade to Microsoft Office 365, consider the free LibreOffice for Mac. It works fine for me.

On the new update (macOS Catalina), Apple no longer accepts 32-bit apps like old versions of Microsoft products. You can see for yourself (through finder or activity monitor) which apps are 32-bit.