Thanks Anshad for your good suggestion.
Now I am thinking of three recovery processes/methodology.
I .Cloning with ddrescue. Advantage: 1. Unlike conventional imaging/cloning software, it can do bad sector recovery as it clones with specified no. of passes. 2. Anshad Edavana can help with his experience. Especially with the second command. We are going to give only two commands and then sit and relax till the cloning is over.
Since all the partitions are intact, I see no problems in ddrescue recognising the problem drive. In the other thread , the first one in Seven Forums where it was recommended, the OP Jon Snow reported that it would not recognise the problem drive. Now we know for sure that was because his drive had gone dead long before.
Requirements: 1. A pendrive to write the bootable ddrescue ISO 2. A formatted empty external drive of not less than 500GB. ( I am not sure of the the ddrescue log file size which it will create. We may not afford to lose it for want of space. So maybe a 750GB or 1TB drive???)
(During the initial phase of this thread, with the OP's sluggish Windows with the problem drive connected, we made a marathon effort to make a bootable pendrive with PW ISO with the onetime boot menu key for the OP's motherboard not known. Thanks to Slarty's find we could get over it and the OP is now well-versed in creating a bootable pendrive and booting from it.)
II. TestDisk: The first and only screen of Windows Disk Management the OP presented after a long read by Windows shows all logical partitions in the drive as RAW. So I would consider using TestDisk > Advanced File utilities to report the health of BootSector/backup Boot Sector and whether an MFT repair will be required all of which it can do hopefully. If these are the only cause of the problem ( like corrupt MFT but not caused by bad sectors), if repaired his drive should be back in shape and the OP can directly list the files and copy those into the external drive. May be as suggested by Anshad which I include now after his previous post on Seatools for DOS, a first run by SeaTools to repair badsectors and then TeskDisk may be a better option? ? Or should we stick to only TestDisk?
Requirements: 1. Two pendrives one for TestDisk and one for Seatools for DOS depending upon which course is decided upon. 2. Same formatted empty drive of 500GB capacity
III. Try Live Linux and copy the files. Distros: Peppermint -1. Golden Tutorial 2. Mate- whs Tutorial and I think Slarty is authoring one 3.Lucid Puppy - jumanji 4.Ubuntu - ICit2lol
Advantage: Authors 2.(Slartybart) 3. and 4. are live on this thread to give an interactive support which the OP may need in dealing with the specific distros.
Disadvantage: 1. No bad sector correction Solution: Seatools for DOS followed by Live Linux ??? 2. OP's inclination to undertake the Linux load also matters.
Requirements: 1. Two pendrives one for the live Linux ISO and one for Seatools for DOS again depending upon the course to be decided 2. The same formatted external HDD of 500GB capacity.
I am not sure which one to go for

.It is for the Jury to decide. I have only presented the possible scenario for experts' opinion. Jurors: 1. Slartybart 2. Anshad Edavana 3. Icit2lol ( who are already in) and 4. Other's who may want to throw themselves in with their opinions.
There may be small holes here and there in my perception and presentation. Those obviously need to be filled up. Bad section repair.
My day is over. Dinner, coffee and then bed.
