are you saying they are listed but clicking on them displays nothing. This is very common if you allow your anti virus to scan Thunderbird and email for a virus. They tend to throw out the baby with the bathwater by deleting everything instead of leaving well enough alone. MAlware in a Thunderbird email is as close to harmless as any web page can be, without the hevey handed deletions.

Hi Matt, thanks for your email. No, the emails before the 21st June have completely gone from my inbox. My sent folder is OK. This has happened to before earlier in the year. It's almost like they have been automatically archived. Very frustrating. Can you help please.

Matt said

are you saying they are listed but clicking on them displays nothing. This is very common if you allow your anti virus to scan Thunderbird and email for a virus. They tend to throw out the baby with the bathwater by deleting everything instead of leaving well enough alone. MAlware in a Thunderbird email is as close to harmless as any web page can be, without the hevey handed deletions.

This has just happened to me too. As it happens, I just installed a new anti virus program, so I now went and looked in their quarantined folder but it is empty. There is no report of it having found anything. I'd better give some more details. I noticed this morning that one of my folders was missing. Happens to be my most important folder. I panicked, then decided that I must have somehow accidentally deleted it, so looked in the deleted folder, but there was nothing there. I was very upset, recreated the folder and was overjoyed when all the messages re-appeared in it. That is, until I noticed that they were all empty. I then discovered that most of my folders, including the Inbox are all the same. There are a few folders however, that didn't seem to have suffered the same faith. Having searched the entire hard drive for them, I doubt that there is a way to recover them (sorry to say, I have been very lax about backing up) but I do want to know what went wrong, so that this never happens again