To make things clear:
There is no virus in the file:
https://www.virustotal.com/de/file/5ac5 ... 393160495/If your AV detects a false positive, you can safely disable it for the download (and consider getting a new one...)
You need to 
unzip the file and copy to dinput8.dll into your 
game directory (where 
BFBC2Game.exe is).
If you get a "bad version" error, you are using a modified version of the game that is not supported by Nexus (e.g. NoSteam). Get an original copy of the game.
Also, the 
Global Forum Rules apply in this thread as well as in any other. Follow them or take the consequences.