The only password to a computer is a BIOS-password. But I think you mean she "forgot the password to her Windows account."
A common way to reset is is to use a program called NTPASSWD (google that). Also see the first 3 programs in https://www.lifewire.com/free-windows-password-recovery-tools-2626179
There might be issues if her computer is a newer UEFI or Windows Signature computer that doesn't allow all boots from a CD/DVD.
And, of course, you can go back to factory conditions or reinstall Windows, but it's much more work to get it back to what it is now, including all data she forgot to backup.
A few tips for the future:
- Make a PASSWORD RECOVERY DISK (google that for the version of Windows that is installed)
- Make a second administrator account with a password that only YOU know. If she forgets her, you login into that and reset hers from Control Panel. It's always a good idea to have a spare admin account, just in case the one normally used gets corrupted.
- Delete the password for her account. Then she never needs one.