I had to format my pc, so i copied all my games from steam->steamapps-> common, i copied the common folder in which the games are present, so after reinstalling the OS, i installed steam nd copied back the common folder with games in it. Inside the steamapps. And logged in, in steam, it starts to download the whole game again. i dn't wanna download again, it's a huge amount of data, with my internet it gonna take weeks. somebody help. apologies for the bad english.
You have to go into your steam settings and point it at the games library. You should be able to browse to the directory where they are and set it. Your library should update to include the games. It will run the "first run" every time you start a game (to install all the dependencies like DirectX etc.)