Steam mods now only through store!
The mods for Half-Life 2 that got released on Steam before are now NOT in your UNINSTALLED part anymore of Steam. If you want to grab the mod you need to go to the Steam store and hit download from there. This is probably also the best since otherwise your Steam games window would be flooded in the future with mods for games 😉
We just got the confirmation from Valve on this.