Thanks for answers.
This is an IMAP account, so Opera should be getting information from the server. If you click on a message to read it, does it show the correct data in the message fields?
After opera restart, the window looks normal - it shows correctly body of the mail where the cursor is in the list of subjects. If I click on some other mail in the list of mails/subjects, this subjects becomes selected (blue color) but subject text becomes invisible and the message body becomes "No message selected".
Right click on a message and choose "view all headers and message". Are the headers there at least? If so, I think Opera's database is just messed up. (The database duplicates some info from the stored mbs file and uses that copy of the info.)
It works on the mail where the cursor was immediately after opera restart. Also if I click on mail B and return on mail A then it will not work again on mail A.
You can run a database check to see if it fixes it.
Recovery log says database consistent. (BTW the link you mentioned doesn't work for me, I used this one.)
If that doesn't work, try deleting .opera/sessions/autosave.win. If that doesn't work, try renaming .opera/operaprefs.ini. If that doesn't work, you can try reinstalling Opera over the top of itself to repair program files.
Tried it but it doesn't work.
If none of that works, you'll probably have to start over with a new mail folder. To do that, you'd right-click "All Messages/Sent" and export it to an mbs file.
It asks to download missing bodies before exporting. I click Yes but nothing happens.