iCloud option is greyed out and some files in Documents directory missing

I am using MacBook Air M1 running macOS Sonoma 14.5. I have a folder in the Documents directory where I saved my presentations (in different sub-folders each for a different presentation) made in latex beamer. Surprisingly, I found that in some of these sub-folders, my *.tex* and *.pdf* files are missing, while other files such as *.aux*, *.bib* etc. are present. A quick Google search suggested to check for the iCloud setting, which I find totally greyed out. Nothing comes on the screen when I click on it. What could possibly be wrong with iCloud? Is inactivity of iCloud responsible for my lost files? More importantly, how can I get my files back?