Menu bar disappeared – what to do?

My default language for the site is Latvian. The interface for admin panel is in latvian. Recently I added russian to my site and clicked on russian flag icon at the bottom of the left menu bar… the whole admin desk switched to russian and the menu panel disappeared. I can not switch back to latvian or any other language. There are no menu anymore (pages, posts, settings, plugins etc.).

Please help me. How to solve this?

Thank You a lot,
Agris