The community is also a great place to check out. Try these places for help from other users:
If you're encountering issues with launching Call of Duty Black Ops 2, make sure everything installed smoothly.
Exit Steam entirely.
Browse to your Call of Duty: Black Ops 2 installation folder (Usually C:\Program Files\Steam\steamapps\common\Call of Duty Black Ops II\)
Run the following installers:
Reboot your computer and test any issues again. If the issue persists, contact Black Ops 2 support.
If you have been banned from the Call of Duty: Black Ops 2 multiplayer or zombies mode but are not VAC banned, you will need to contact Black Ops 2 support for more information. However, like VAC bans, Black Ops 2 cheating bans are not removable in any case.
VAC bans are not negotiable, and are issued and enforced regardless of the circumstances under which the cheating infractions were recorded. Steam Support cannot remove a VAC ban in any case.
You can find more information about the Valve Anti Cheat (VAC) system here:
If you encounter a cheater in a game, you can report them using their Steam Community profile:
Do not use the Steam Support ticket system to report a cheater. The method that is outlined in the Reporting Suspected Cheaters link is the best way to report a potential cheater.
If the above does not resolve the issue and you are running Windows 7 or Windows Vista, please complete the instructions in our Windows 7 and Vista Troubleshooting FAQ.
If you are running in Windows XP, take the following steps: