I deleted my WTF and Cache folders (standard thing to do when you experience weird things) and now I can't start WoW anymore.

I get this message in WowError:

"This application has encountered a critical error:

The system cannot find the file specified.

Program: C:\Users\Username\Downloads\World of Warcraft - Cataclysm 4.3.4 (15595)\Wow.exe"

Why does this happen and how do I fix it?