Upgrade from Windows 7 - big problem

I was running windows 7 without problem.
got the small white 'window' seducing me to windows 10 which i gladly accepted.
i liked it for a while.

one day i couldn't boot. i went over all possible problems since i am an intermediate computer person.
i had to work, so i swapped out the problem drive with a spare drive, reinstalled windows 7 and my critical programs, and was on my way.

[btw, the windows 7 installation was on a new hard drive that had been running windows 7 for only about 4 months.]

i hooked the windows 10 drive thru a new, tested, quality external drive. but i couldn't even open the drive in explorer. the drive was recognized by explorer, but couldn't access any folder or file. i've tried many other things. so i'm here.

any help is greatly appreciated. :)

Hi szszo, so basically you're wondering how to access the drive you used when you upgraded to Win 10- which isn't allowing you to read it normally. Not sure I understand 'thru a new, tested, quality external drive' - I assume you connected the drive as an external drive to a PC.

1. Have you tried running chkdsk on it? You say the drive is recognised when it is plugged in.
2. If you really really can't access the drive properly, a couple of things could have happened (beyond some limited sector or cluster corruption.
a. Hardware fault (ok, you said it's quite new).
b. Corruption of the Master File Table (assuming NTFS format).

In the latter case, use a good partition manager and see what you can see. Some partition managers also support repair/regeneration of this, and recovering lost partitions, and there are also dedicated programs for this.
Good luck!