you do now use the harddrive as an externalhd? if you have formated the drive then it could still be possible but expensive. but if you have overwriten all with zeros or on the place where the wallet was stored was writen something new i think you have lost the wallet then.  With some recoverytools you mainly get out pictures/doc/vids back. i havent found one who could recover dat files. i tried my self one time to test if it works. it didnt. and professionals was writen would use mostly the same tools i tried.