|Does the drive show the normal capacity in Device Manager?|
By default, Windows automatically prevents certain files from being accessed by a non-system administrator.
To boot from the drive, turn off the laptop but leave the drive attached. Turn on the laptop, and you should see a brief prompt to enter a 'Boot Menu' by pressing F10 or something. If this doesn't show up, you'll have to check the manual for which key to press.
In the menu you should see some options like Hard Drive, Network, CD/ROM, and USB. It'll likely be USB, though if you see multiple Hard Drive entries, select the one that says the proper size.
No, I highly doubt booting from the old drive would 'hurt' your computer...the worst that would probably happen would be that it simply won't boot from the drive, and we'll have to find some other way to access the files.
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