Hello pstKSU,
Thanks for reaching out to the Apple Support Communities! From the screenshot I can see that you're not seeing the items under Finder > Locations that you expect to see.
Great thinking to check Finder > Preferences for any changes. Let’s begin with some basic troubleshooting, if you haven’t done so already, and then work our way toward more complex ones. This will help us to isolate the issue further:
1 - First, quit all apps. If an app will not quit, follow these steps to force it to quit: How to force an app to quit on your Mac.
2 - Restart your iMac: Go to the Apple menu in the top left corner of your screen > Restart. See if there is any change in what's appearing under locations in the Finder Sidebar.
3 - If the issue persists, restart in safe mode and test again: Use safe mode to isolate issues with your Mac.
4 - If still occurring in safe mode you’ll need to create a new user and test it out again. This article will show you how: How to test an issue in another user account on your Mac.
If there is no change with the new user, or you're receiving an error message, be sure to provide that information.
All the best.