Finder stopped showing the content of a text file

I have been using MacBook pro-2017 for about a year, in the mean time I have added a couple of quiclook generators (e.g. QLStephen.qlgenerator) for various services for the Finder. For quite a few days it was working good, but now, I encountered a strange problem. Nowadays I can not see the contents of any file in the finder, e.g. when I click on a a.txt file it shows no contents, but when pressed Shift key it shows the QuickView of the item. How to restore the original settings of the Finder? I tried deleting all the quicklook plugins, but still, the problem is sustained. Attempt: cd ~/Library/QuickLook sudo mkdir backup sudo mv *.qlg* backup/ qlmanage -r killall Finder PS: I tried also deleting all the contents of QuickLook and restarted the computer. Still it does not work. Maybe I have to reset the Finder settings, but I don't know how? Note that here the a.txt is not empty but Finder shows nothing. **How can we make the Finder show the contents of this file?** **Update** Backed up and deleted the QuickLook folders from the computer. sudo mv /Library/QuickLook ~/library_quicklook sudo mv ~/Library/QuickLook ~/home_library_quicklook sudo rm -rf com.apple.quicklook.ui.helper.plist sudo rm -rf com.apple.quicklookconfig.plist sudo rm -rf com.apple.QuickLookDaemon.plist qlmanage -r qlmanage -r cache killall Finder Still does not work. Related links: https://www.cnet.com/news/fixing-quick-look-issues-in-os-x/