Hi Igor,
This happens from time to time. Here is what I do:
Go to Dashboard > Settings > Advanced > Site History and choose the NEXT TO LAST publishing.
Typically this works. I have experienced a glitch in the code before, where I had to go back a few more publishing states.
Last ditch effort would be to duplicate your site, but that’s only AFTER you have talked to Customer Support. Duplicating the site seems to “unclog” any bugs. I would do this if you have blog post, as the settings for the post will need to be re-addressed. Very tedious.
Keep me posted and good luck!
Teejay