a couple of questions. Are you transferring from one manufacturer to another? They may be able to guide you if so. Are we talking about both drives being of the same type i.e. disk/solid state etc.? When I converted to solid state the file transfer bugged out on me several times and took hours to complete even though it was not a big amount stored on the old drive. I was advised by a tech to use the drive transfer program recommended by the manufacturer of the new drive and it did help a little but the old drive had less than 700GB on it and it still took hours for it to transfer but at least it did complete it finally. I suppose you could try drag and drop but at the size of data you are referencing that seems like it could be a long time too. Could you upload the old drive to a cloud backup and then download to your new drive? Also are you able to open these old files yet on the old drive? If so then it doesn't seem to me that the sectors would be so bad as to be the issue. Are you able to take the old drive back to a restore point before you had used any of the cloning apps? You could have a remnant of one or more giving you a problem for some reason. Remember that with much of this crap even when it's uninstalled all of it may never completely leave. I've found old remnants of software in the oddest of places even years later.
As far as your system now asking for an admin password that seems foreign to you I would ask if you at any time had your computer at the tech shop for resolution of problems or upgrades? A few years back I had a somewhat similar thing happen where I was doing something requiring an admin password and mine failed. A few months prior I had a tech do some troubleshooting/upgrades/repairs and in doing so it turns out that he had used a new password but did not tell me. So when the time came the one I thought would work did not. The chk disk saying the drive is in use may be because of the transfer you already started is still trying to complete in the background or you may have your system using some sort of background disk monitor that is interfering. I know some techs recommend disabling any utilities/anti-virus etc. before making drive transfers.
Just some thoughts about the problems you're having. It's always supposed to work and it does until it doesn't.
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