I'm willing to try anything.
Though, like I've said before, this is all spooky stuff to me and I'm not sure I'm doing it right.
I opened AppleScript Editor.
I found myself facing a blank window pane above and another below.
Into the top pane I pasted mkdir ~/.Trash (I didn't put in the quotation marks that were around it in your instructions)
I clicked on Run
A drop-down box appeared that said:
Syntax Error A unknown token can’t go after this identifier.
So then I cleared the window and did it again, but with the quotation marks.
"mkdir ~/.Trash" then appeared in both the upper pane and the lower pane.
Is that a message that the folder exists? I dunno.
So I put "chown $UID ~/.Trash" into the upper pane, hit Run and watched it appear in the lower pane as well.
Still no magic.
So I ran "chmod u+rwx ~/.Trash" and it also reappeared below.
Then I closed AppleScript Editor, and saved the script at the prompt.
Finally, I tried again to drag my test file to the Trash. But, no great surprise, nothing had changed.