AC$ is not a file you can recover: BAK and SV$ are the only ones that can be
renamed to DWG and accessed, and only if you took the time to turn on BAK
file creation, and setup AutoSAVE respectively.
ISAVEPERCENT=0 and SAVETIME set to 15, plus BAK file creation turned on and
you using SAVE often is the safe way to use AutoCAD.
--
Dean Saadallah
Add-on products for LT
http://www.pendean.com/lt
--