I upgraded to Catalina and now my microsoft office won't work and I need it. How do I get it back

If you have Office 2011 it won't run under Catalina. You need to upgrade to Office 365 or Office 2019. If you have Office 2016 there is a free update.

https://products.office.com/en-us/compare-all-microsoft-office-products-b

What version of Microsoft Office did you have?

Office 2011 and earlier will not work in Catalina. This has been warned for the past 2 years, and the Catalina installer should have further warned you about it before installing it.

Office 2016 has an update: https://docs.microsoft.com/en-us/office365/troubleshoot/administration/office-2016-for-mac-64-bit-upgrade

365 and Office 2019 should work without issue.

If you have Office 2011 or earlier you will need to buy a new version of Office to work on Catalina: https://products.office.com/en-us/compare-all-microsoft-office-products?activetab=tab%3aprimaryr1

Alternatively you can try out free alternatives such as Libre Office or Open Office or even Apple's own Pages, Numbers and Keynote Apps.