How to know if OneDrive is working....? or Why is my Onedrive files missing?

Please review this article from Microsoft to know what your OneDrive icon means:

https://support.microsoft.com/en-us/office/what-do-the-onedrive-icons-mean-11143026-8000-44f8-aaa9-67c985aa49b3

If you don't see the blue cloud*, that could means OneDrive is not running on your computer because it crashed or it is set to not auto start.

Either situation above, just go to the Windows button (bottom left side of the screen) then look for OneDrive's blue-ish cloud icon in the program list or on the Start tiles and launch it. It should immediately start syncing. Once the sync is completed it would be best to restart your computer.

You might want to see how long your computer been running, https://support.orbis.org/a/solutions/articles/15000036562.. Your computer will service you best if you restart your computer at least twice a week.

*Where to find your blue cloud: