This answer doesn't directly answer the question, but still will result in the same end result.

The Arduino IDE uses temporary directories to store build files, including the original sketch as well as the HEX and intermediate files.

On a Mac, these are in /var/folders by default, and on a Windows machine they are in …\Local Settings\Temp\ (which depending on the version of Windows could be in several places).

I've found that especially in Windows, these build files don't get deleted when you close the sketch or IDE, so they may exist on your machine for far longer than you would think.

Also, by default, Crashplan, Backblaze and Time Machine back-up these locations, so even if they have been deleted, they may still be in a backup.

The advantage here is that you will recover C code rather than ASM.