All newsgroup messages suddenly disappeared

[Pimpom]

I've been using Thunderbird as my Usenet newsreader for several years and never had a problem until now. When I turned my computer on for the first time today and tried to read newsgroup posts, I found that they were all gone, including those that I read and posted just before going to bed late last night. The headers are still there but the cached message bodies had all disappeared, literally overnight.

Moreover, I now cannot download messages. It says "Connecting to news.albasani.net" as usual at the bottom (albasani is my newsserver), but only for a fleeting moment and then does nothing else.

I use default settings except for line wrap length and have not changed anything in TBird, antivirus (Avira) or firewall settings. CCleaner analysis says that there's 1345 KB and 206 files in the Thunderbird Internet Cache.

Clarification and suggestions please?