Check the overall system requirement of the game to see if everything is set. PC Specifications & Technology Enhancements Intel
If it will still not work, try verifying game integrity.
Go to Steam>>Library>>Right-click on BO2>>go to Properties>>Select Local Files>> Verify Game Integrity
You need to meet the minimum system requirements for you to run the game properly. Here are the requirements for the game.
OS: Windows Vista (Service Pack 2) or Windows 7; (Windows XP not supported)
Processor: Intel Core2 Duo E8200 2.66 GHz or AMD Phenom X3 8750 2.4 GHz processor or better
Memory: 2GB for 32-bit OS or 4GB for 64-bit OS
Graphics: Nvidia GeForce 8800GT 512 MB or ATI Radeon HD 3870 512 MB or better
DirectX®: DirectX® 9.0c or later
Hard Drive: 16 GB free hard drive space
Sound: DirectX® 9.0c or later
Check your system