Press the on your controller and select Manage Game Content . Scroll to Language Data . Locate the English pack and select the Download icon .
Highlight and press the Menu button (three lines). Select Manage Game and Add-ons . Download Modern Warfare 3 English Language Pack
If you are playing the older version of MW3 and the platform options aren't working, you may need to manually swap files. Press the on your controller and select Manage Game Content
Check for any available in the "Ready to Install" or "Add-ons" section. Manual Fix for the 2011 Version (Advanced) Download Modern Warfare 3 English Language Pack