Older auto-save backups for Word documents (.asd) may be most likely only recovered (back to .doc) using specific older versions of Word, up to version 2007 to be precise. Other than that, it will be probably impossible to recover the document from .asd by other means. Just a simple rename from asd to doc apparently does not work.
Unfortunately, no 3rd party asd file opener exists, so using the recovery function in Word remains the only option to achieve asd to doc conversion.