I updated to big sure OS and it deleted files and caused my microsoft products to quit working. They are older version. I migrated back to Mojave and now cannot get my Exchange Email account set back up in Mac Mail. Keep getting a blank password screen or an unrecognized password. How do i get email back up.
The best way is to visit http://www.outlook.com/ on the web. Stand alone email clients are no longer available for Mojave from Microsoft that support it.
Office 2021 Mac is available for stand alone Office support on Catalina and later.
You can install Catalina on a separate partition using Disk Utility. Its license subscription won't run out until 2026.
https://learn.microsoft.com/en-us/lifecycle/products/microsoft-office-2019-for-mac
I recommend either getting an external hard disk of at least 256 GB or if you have at least 100 GB free use Disk Utility to make a separate partition before installing Catalina or later.
Current Office sysreqs are the current and two previous versions of macOS. Today that is only Sonoma, Ventura, and Monterey. See this Microsoft document:
Is Apple OS Mojove still able to interface mail with Microsoft exchange
