Preload? WHY!?!?!

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I bought Left For Dead 2 about a year and a half ago. A while ago, it told me i had to preload it for no reason, and i couldnt play. I tried to preload it, but the launcher said "the steam Servers are too full to handle any more preloads of left for dead 2". I was told by some people to uninstall all local content from my computer, and now it's not showing up in my steam library. I even tried going back to the steam store to see if i could get it there, but its telling me i dont own the game. someone help!