Shouldn't need to buy a license. During the install, at the point where it wants you to enter a license key, click the "I do not have a license key" thing at the bottom, and continue the install. It should pick up that Win 10 was previously licensed on that particular computer, and automatically activate.
Windows 10 sure seems to break a lot. Good think Win 10 is super easy to install.
Not Linux. I’m ok with Linux but my wife is not. Linux is out.
Linux is all my wife knows.
Curious attitude, given Windows has been morphing quite a bit, the last couple versions (8, 8.1, 10).