The hidden Trash folder in your home folder has somehow been replaced by a file. The easiest way to solve the problem is to take the steps below. This procedure does not delete anything, but on general principle you should back up all data before you begin, if you don't already have a current backup.
Please triple-click anywhere in the line below on this page to select it:
mv .Trash $TMPDIR; mkdir .Trash; killall Finder
Copy the selected text to the Clipboard by pressing the key combination command-C.
Launch the built-in Terminal application in any one of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad and start typing the name.
Paste into the Terminal window by pressing the key combination command-V. I've tested these instructions only with the Safari web browser. If you use another browser, you may have to press the return key after pasting.
Wait for a new line ending in a dollar sign ($) to appear below what you entered. You can then quit Terminal.
