none of the ways suggested to force quit finder on my mac air is not working. restarting does not help too. any advice?

From your Finder "Go" menu > "Go to folder" then copy & paste this file path:

~/Library/Preferences/com.apple.finder.plist

Click Go.

Delete the plist file.

Then, restart, or log out and in again.

(You may have to reset some Finder preferences the way you like them)

Boot into Safe Mode and see if Finder works as expected:

Use safe mode to isolate issues with your Mac - Apple Support

Only com.apple.finder.plist.

Why do you want to force quit Finder?