Applications folder missing from Finder Favorites after FaceTime Internal Error

It seems that I've always had technical issues opening FaceTime so that I had to reopen it again because the video screen was black or not working. However, this time the video screen didn't show the seond time I opened it and my computer froze with that spinning wheel and pop-up message FaceTime Internal Error. I clicked on Finder while it was still spinning to see if I could access the FaceTime camera in PhotoBooth or Zoom. Although I was able to open PhotoBooth, my Applications folder was no longer showing in Finder Favorites/Shortcuts after I did so. This is the only place I know where to locate applications. I tried to find apps in Launchpad, but you can't delete/update apps there. When I clicked on Zoom in Launchpad, I found that there is no camera linked with my Zoom account anymore. I guess FaceTime is the camera that was linked to it.

Then, this week my screenshot function (that come with MacBook 2015) no longer works. I did have a virus threat that I corrected with MalwareBytes last week, but I no longer see MalwareBytes in launchpad.