Overview
If you find a game(here we take portal 2 as example) you installed appeared as uninstalled,but the game (portal 2) file is still on you disk.Follow these steps:Find this folder:SteamSteamAppsYou should find several acf file name like this :appmanifest_*****.acfOpen the game(portal 2) store page, for example: http://store.steampowered.com/app/620/and here “620” is the number you need.Try to find the appmanifest_620.acf,if it does not exist,create one file with that name(if you do not know the method,google it). PS:Control panel–>Folder options–>View–>Hide extensions for know files types, uncheck it. Create a new txt file, name its full name as ” XXXXX.acf”, not ” XXXX.acf.txt”, done.open the appmanifest_620.acf ( if it is not portal 2 , use your game number instead of 620.)it may looks like this:Originally posted by author:”AppState”{“appid” “620””Universe” “1””name” “Portal 2″”StateFlags” “66””installdir” “Portal 2″”LastUpdated” “0””UpdateResult” “0””SizeOnDisk” “0””buildid” “0””LastOwner” “0””BytesToDownload” “0””BytesDownloaded” “0””AutoUpdateBehavior” “0””AllowOtherDownloadsWhileRunning” “0””UserConfig”{}”MountedDepots”{}}Added in 2019/01/08, the portal 2 acf file here on my disk changed as I posted below, you may try with it instead of the quote above.Originally posted by author:”AppState”{ “appid” “620” “Universe” “1” “name” “Portal 2” “StateFlags” “4” “installdir” “Portal 2” “LastUpdated” “1546915851” “UpdateResult” “0” “SizeOnDisk” “12772699651” “buildid” “3261795” “LastOwner” “76561198124511924” “BytesToDownload” “0” “BytesDownloaded” “0” “AutoUpdateBehavior” “0” “AllowOtherDownloadsWhileRunning” “0” “ScheduledAutoUpdate” “0” “StagingFolder” “1” “UserConfig” { “language” “english” } “InstalledDepots” { “624” { “manifest” “6415342253277896102” } “622” { “manifest” “2180841775043336221” } “621” { “manifest” “5315625579909971887” } “323180” { “manifest” “4821416258997072443” “dlcappid” “323180” } } “MountedDepots” { “624” “6415342253277896102” “622” “2180841775043336221” “621” “5315625579909971887” “323180” “4821416258997072443” }}If it looks like this( steam maybe update in the future,so I suggest you backup your file and try),change “BytesDownloaded” “0” to”BytesDownloaded” “12715331543”,and save it.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. For if you open more acf files, they are different from each other in details.Restart the steam,and install the game(portal 2) with steam,now it should begin to verify your game file instead of downloading it.———————————————————————————————————-It maybe take a little time, it depend on your computer.
About this guide
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”.
There are so many games in Steam, user may downloaded 100G file on the disk, it may takes 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 open it. But still when we open it, Steam knows which game is updated and update it, so it does check something.
Searching in Google, not hard to find the information of acf file, but the game updated many times, I didn’t find the updated one. Still I didn’t find another friend who had the updated game and online to help me get the right file at that time.
So I focused on how to let Steam check the files there. The acf file is easy to read,
“BytesDownloaded” “0”
“AutoUpdateBehavior” “0”
that tells Steam nothing downloaded, and the behavior tells Steam downloading this game automatically or not. I think if I change “downloaded” to none zero, Steam will read the disk to know which files have been downloaded. It works at that time.
Still Steam may change it sometime, so feel free if it doesn’t work for you.