How to perform deleted files recovery from corrupted external Mac HD?

Could you provide some details; for instance

i) Is your hard drive appearing in Disk Utility?

ii) Have you checked the SMART using WD or Disk Utility?

iii) You didn’t mention any instances of physical damages i.e. clicking, buzzing sound hence I consider your hard drive logically damaged

Solution

i) If your external drive is backed up then erase the utility either through Disk utility or with Terminal

ii) You can also create image of your external hard drive and reformat the hard drive

iii) If all fails, then the last bet is data recovery. Try Macintosh data recovery http://www.macintosh-data-recovery.com/ to recover data from failed external hard drive