Thank you all for your suggestions and tips.
I bought a new hard drive, WD My Book 4TB External Hard Drive which works fine except that it can’t backup files from my system C drive. I posted a new topic about this problem, this is a link to it:
Regarding the old hard drive, someone from WD called me on the phone and tried a number of steps to troubleshoot the problem but this didn’t help and he concluded that drive has a problem that can’t be fixed. The warranty of the hard drive had expired several months ago but he said they will replace my hard drive anyway which really impressed me and made a very happy customer especially after the fact that I just had bought a new hard drive from WD after considering other brands.
Anyway, he said I can use a service or try myself data recovery before sending the dirve for replacement. While I would like to recover some of the files on that hard drive which had no backup copies on my other hard drives, they are not that important to justify considerable payment. I will try the free solutions suggested from the replies here and will update you on the progress later
Thank you
