INSTRUCTIONS FOR ENGLISH/ ANY LANGUAGE USING ISO OF GAME:

1. Install your English or any other language version of the game using
your DVD ISO / torrents. There is a link where you can find torrents:

http://www.torrentz.com/search?q=modern+warfare+2  (The game has size about 11Gb)

2. Log onto steam and activate your CD-KEY( My Games>Activate a Product on
steam)  Right-Click  CODMW2 Multiplayer   >properties>language>choose
Desired language. Refer 1. 

3. Right-Click on MW2 Single player & Multiplayer and Pause updating

 
4. Close/Logout of steam and navigate to (\Program Files
(\Activision\Modern Warfare 2)  Cut/Copy the folder called Call of Duty
Modern Warfare 2  And paste it in \Steam\SteamApps\common\ to replace the
Steam created one.

5. Login to steam Right-Click on MW2 Multiplayer and Resume Updating,
LEAVE SINGLEPLAYER PAUSED!

6. Once Updating has completed Right-Click on MW2
Multiplayer>Properties>Local Files>
   Verify integrity of game cache

 
7. Steam will automatically download the latest Updates for multiplayer

8. Next update singleplayer

9. Steam will automatically download the latest Updates for Singleplayer

10. Go to \Steam\SteamApps\common\call of duty modern warfare 2 and into
zone and check that there is a russian folder and an english folder about
the same size

11. Go to main and you should see localized_russian_iw00.iwd to
localized_russian_iw08.iwd aswell as localized_english_iw00.iwd to
localized_english_iw007.iwd

12. Go to http://cdkeys.eu5.org/localization.txt and
replace the localization.txt

THATS IT!

credit to Niko for the singleplayer intructions :)

ERRORS

If will be error with this files:

patch.ff
patch_code_pre_gfx.ff
patch_code_pre_gfx_mp.ff
patch_map.ff 

Download this archive and unpack it to your 

\Steam\SteamApps\common\call of duty modern warfare 2\Zone\English folder 

and replace existing files.