

That tells Steam nothing downloaded, and the behavior make Steam downloading this game automatically.The best would be change it to the right figure which I have not. So I focused on how to let Steam check the files.

Still I didn't find another friend who had the game and online to help me get the right file at that time. Searching in Google, not hard to find the information of acf file, but the game updated many times, I didn't find the latest one. Actually when we start it, Steam knows which game is outdated and update it, so it does check something. There are so many games in Steam, user may downloaded 100G file on their disk, it may take hours to check all the file to be correct, so it is impossible for Steam to check all the files in the starting( you can do that with option "verify integrity of game files" in the properties), or we will wait Steam to start more than minutes every time when we start it. When I happened to lost 1 game in the library of Steam, and I found the game folders and files still there, I think there should be a way to tell Steam:" the files are here, plz check out".

It may take some time, that depends on your computer. Restart the steam,and install the game(portal 2) in your steam library,now it should begin to verify your game files instead of downloading it. Because if you open more acf files, they are different from each other in details. PS: don't forget to change the "name", "installdir" and "appid", also I don't know whether to change "Universe" and "StateFlags" or not, it would be best to search the formation of your game acf file from Google in case your acf file doesn't exist. "BytesDownloaded" "12715331543", this number you can take randomly, then save it.

If it looks like this( steam maybe update in the future,so I suggest you backup your file and try),change
