This will activate the Recovery Mode and from here you can format and install a new copy of OS X.
However, not all Macs are capable of doing that, we have no details about your Mac, but there is information available at http://www.apple.com/osx/recovery/ that you should read
BEFORE you do any of that though, make sure that you have a COMPLETE BACKUP of all your important data.
Documents, pictures, music, etc.
P
several of my applications are corrupted and there are problems with OSX as well. i sent away for what i thought would be disks. now i am supposed to download from the ap store?
how does that work, to erase and then not be able to load software?
Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic