Players often delete language packs they don't use to save space; if you accidentally deleted the English files, you’ll need to re-fetch them. How to Install on PlayStation (PS4/PS5)
On PC, use the "Scan and Repair" (Battle.net) or "Verify Integrity of Game Files" (Steam) feature to ensure the pack isn't corrupted. Call Of Duty Modern Warfare 3 English Language Pack
Find the in the list, check the box, and select Save changes . How to Install on PC (Battle.net & Steam) Players often delete language packs they don't use