OK, solved. But this plugin is dangerous!
How I solved it? I went to history, opened plugin's page and reloaded. Haha, pretty stupid but it worked. (plugis Advanced ajax..... has been turned off because could not find directory)
And there's old post:
HEY! I've just installed "Advanced AJAX Page Loader" and my site is broken!
I CAN'T DO ANYTHING!
When I open my site it shows "error connecting to database"
What I did later:
- opened FTP, wp-content -> plugins -> deleted this folder
And nothing changed!
I CANT DO ANYTHING!