Hi,
This is the wrong forum for Call of Duty: Modern Warfare.
This forum is for technical support on Blizzard’s Classic Games — Diablo II (2000) mostly.
You’ll find details of what support Blizzard offers for Activision games here: Having Problems with Call of Duty? Read this first!
Your issue does not appear to be related to installation or update… so you will need to contact Activision Support:
Regards.