Q: desktop folder won't open

I don't know what your did but what is showing is not the Desktop folder but your Home folder, despite what it says in the sidebar. I suspect the "Desktop (original)" is the correct desktop folder. Not sure how you would fix it other than doing a total restore.

You have changed the home permission settings please make the settings like this .

Open pad lock enter admin name & password select staff , click on drop down arrow choose as read , for everyone same as read only , click on gear icon drop down arrow and apply .

close the pad lock & try .

Also an article  : Resolve issues caused by changing the permissions of items in your home folder - Apple Support

I clicked on finder documents pressed command + info & please see the settings in screen shots , as documents , applications , downloads , desktop respectively . These are correct settings , please match in your system also , I think so application screen shot and desktop screen shot must be same .

FWIW, I seem to remember telling you a restore was in order.

Oh ! really that 's too good .

Cheers !

Take care .