Dragon Age: Origins not working on PC

I recently bought Dragon Age: Origins on Greenmangaming.com and then proceeded to download Origins platform, where i inserted my cd key it asked me which language i wanted, i choose english and then downloaded the game, after the download finished i realized that i could not play the game. When i hovered over the game in my library, there was no play option, instead the install option remained. So i clicked it again and got a blank error pop up. I managed to find the Dragon age file in origins game folder and clicked the installer file but got the error of "This version of the Dragon Age Origins - Awakening installer does not support your installed language of Dragon Age: Origins." I have no idea what to do... i can't reisntall the game because it says that the cd key i used is already in use.