Well, that's strange .. why would it update? Did it automatically download some mods which you have subscribed to?
The only way to get Enderal going again is a complete reinstall.
Backup your saves.
Uninstall Enderal completely (not archiving) through the Launcher and clear the skyrim folder by hand. Then download Skyrim again from Steam.
Verify the integrity of game cache on Skyrim. Start Skyrim once and check if everything works. Then quit Skyrim and install Enderal from the installation package again.
Be careful about loading your savegames. They could be corrupted through loading in the Skyrim worldspace.