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I have also used an enclosure to no avail
Just to clarify before going on with some suggestions:
I take it by that that you mean you pulled the hard drive out of the desktop(?) PC case and put it into an enclosure connected to something by USB? If so and what you tried without success was to boot to it you cannot (normally at present) boot from a drive connected by USB to an operational PC. Windows will let you look at the contents of the drive but not boot it up like if it was inside the case and part of the system.
You say that by two ways you can see the drive ... but can you see the contents of the drive -- the various files etc?
If you can fill on all that as well as this bit of my boilerplate
To get you the best advice, would you give us some more information about your system:
The version of Windows that is on it and that you are trying to boot to is Windows 10?
Please say which subversion: Home or Pro and whether it is 32 bit or 64bit (If you don't know but it's a commercial model PC please say the Make and Model Identification which would enable us to look it up.
the Name and Version ID of the Norton product that you are using -- Help or Support / About is where that is, in the format of nn.nn.nn.nnn where n is a number.
If you have the COMCAST version of Norton 360 / Security Suite and not the normal retail version please be sure to tell us.
Please also say what internet browser you are using -- name and version number ...
If you get any error messages please give the exact wording of them as well as any other background that could be helpful.
then I have some suggestions that may help you resolve the situation although perhaps not why it happened. But we can touch on that later.
Did you make a recovery disc/thumbdrive from this when it was operational?
I'll be offline shortly until early evening so don't be surprised if you don't get a quick next step from me.