Can you still delete messages using the delete button on your keyboard, the delete button on the toolbar or the right-click delete option? (If you don't use any of these, how DO you delete things? ;-) )

If you do any of these, does it not re-create the Trash folder?

I am sure you can create a new Trash folder (right-click, new subfolder), but you need to use an add-on to set its properties.

I can not delete a message from the specific account/inbox which ever action I try (delete button, click the delete box, right click-delete) I have tried to create a new sub folder under the "wastebasket" and I can create the folder alright, but I can still not delete anything from that inbox.

What add-on is it that you suggest I should use to set the properties right?

Addition: I tried to create a new folder under the trash folder, restarted Thunderbird and the newly created folder was gone again.

As no-one seemed to have a fix, I decided to explore the issue myself. Reading and trying all solutions posted without any success I eventually realized that TB did not create the Trash file after deletion. So I did a quick and dirtyand copied the trash file, not the .msf, from another account. Pasted it and restarted TB. Et voila, it works again. Why it disappeared, why it did not recreate I will never know. But its fixed and perhaps the solution can help someone else.