I lost the source code from one project I did on the company I'm working for and haven't been able to find a Visual Basic 6 decompiler; does that even exists?
I only have the EXE that I've rescued from a user's machine.
For the final, compiled code of your application, the short answer is “no”. Different tools are able to extract different information from the code (e.g. the forms setups) and there are P code decompilers (see Edgar's excellent link for such tools). However, up to this day, there is no decompiler for native code. I'm not aware of anything similar for other high-level languages either.