Alright so I made something off the Creation Kit and uploaded to Steam Workshop/Nexus. After awhile, I decided to go back and edit it. Once I loaded everything up, I searched for the cell and it appears the cell I made does not exist. What is the cause of this?

It could be anything, but with so little information to go off of, its hard to say.
You could provide a link to the mod on the nexus.

You could also click on your mod in the CK and before loading it, click on the details button. It will say what that mod contains or has changed.

http://skyrim.nexusmods.com/downloads/file.php?id=9254 Heres the link to the Nexus, and I will try your other option quick.

EDIT: Figured it out: Apparently the .esp in my folder didnt co-operate with CK, so I added the one from the WinRAR and it now works...odd