My Thunderbird Ver is 38.3.0 - Today my delete button stopped working and I went to the FAQ section on the Mozilla support and found the article and followed the instructions, deleting the directoryTree.json, panacea.dat and session.json I then went to the Mail folder and  I have listed POP.NTLWORLD.COM, pop.ntlworld-1.com, pop.ntlworld-2.com and so on to pop.ntlworld-7.com.

Hi, My Thunderbird Ver is 38.3.0 - Today my delete button stopped working and I went to the FAQ section on the Mozilla support and found the article and followed the instructions, deleting the directoryTree.json, panacea.dat and session.json I then went to the Mail folder and I have listed POP.NTLWORLD.COM, pop.ntlworld-1.com, pop.ntlworld-2.com and so on to pop.ntlworld-7.com. I went into each and deleted the Trash and Trash.msf files, shutting down the trouble shooter window and restarting Thunderbird. The system them re created the Trash folder and it put back the 1329 files. So I went to the delete files in Trash they were then removed, -still unable to use delete at that time. SO I went through the whole procedure again. restarted Thunderbird and still the files all 1329 were recreated . So I deleted them all again and went through the whole procedure a third time. Now after restarting I have a blank Trash box but am unable to delete anything from the Inbox or the junk folder or the Sent folder. I am now at a complete loss...Help please. Steve Bishop

          I have taken the bull by the horns - so to speak - I deleted Thunderbird and restarted the computer. I have mozbackup and do regular backups so I installed the latest one and hey presto all is working again.