Steam wants to redownload half-downloaded game [duplicate]

I was downloading Rainbow Six Siege and I added the texture pack before it finished.

I regretted it and unchecked the tick in the DLC tab, but now Steam is trying to re-download the whole game. I have about 30 GB of the game data in the downloads folder of Steam, but it won't recognize it.

Is there anything I can do to fix this? I don't have unlimited net traffic. And i also don't have the .acf file in the downloads folder,it's been replaced, i only have the game files.

Solution 1:

Taken from here:

After making sure that you have a copy of the game files saved somewhere else, right click on the game in your library, and under the Properties tab select "Delete all local content" (or uninstall the game). Then place the files back into the folder (which you may have to recreate, make sure it is named the same thing and is in the same location). Now try and download the game again, Steam will recognise the files that are there.