I have not been on in a while.I can find my download history but every time I try to download I get an error message?Anyone know how I can get my DLC?

Long story short, you can't the DLC on its own anymore. You can, however, get the C2 maximum edition on Steam. It's 70% off right now and includes both.

But yeah, unless you have a backup of the DLC files, that's the only way you can get them. (or if you already bought them, you *might* be able to located the dlc zips online and put them in the right folder.)