Doesn't matter where you got it stored. As far as I know you can do one or more of the following possibility 3.

1) Go to your steam directory and delete all the .blob files except client.blob and restart steam.

2) Once logged into steam go to your games tab, right click on the game you wish to fix and go to its properties. Simply click the following: "Verify integrity of game cache". This will do a force re-check of your game files stored incase you accidentally deleted something, which will replace only the lost files required to properly run the game.

3) Once logged into steam go to your games tab, right click on the game you wish to fix and go to its properties. Then click "Delete local game content"
This will delete 99% of the game with like 2 or 3 small files left behind which aren't too important. This would be a last case scenario incase the first 2 didn't work since this step takes the longest, as you would have to re-install the entire game.


P.S.

Oh incase I forgot to mention, you and everyone else here should know ALL Valve new release games are always fucked up, and this includes their patches. Their patches to fix problems cause new problems so eventually their patches need patches. Yeah their pretty lazy over there. So expect heavy problems with a new Valve game during its launch. Cause I personally can't remember ever getting a game from them and it ever working right on the first day..... Same goes with a new patch release/new content.

This was weird but i fixed it by moving steam to the os hard drive and reinstalling....