Lost the game from the library (Dota 2)

All kind time of day. Faced with such a problem. During the upgrade, Dota 2 has been crashing the computer, causing the restart. After rebooting and starting Steam discovered that Dota 2 is no longer in the library, but the files remained in the same place. When I point the path to the game, Steam takes it as a third-party not download to it updates. Please help to solve this problem, because I do not want to load the game again. Thank you for your attention.