Programs removed from Finder side bar

After my latest Big Sur update to 11.4, I noticed that several links in the side bar of finder have disappeared. Yesterday I tried to access my Documents folder from the Finder, which used to be listed in the side bar, and when I located and opened the folder there was nothing in there. I used 'Get Info' on the folder and it told me "You have unknown access" and so I was unable to reset permissions through it. Fortunately I have the Documents folder also in my Dock Bar and when I clicked that, all my files showed. So how do I reset the permissions through Terminal or can I not being an OS folder. Furthermore it will not allow me to put Dropbox back in the side bar