As I recall,"Nothing Else Matters" is in the key of Eminor.Rather than spend your time trying to "nail" the solo note-for-note,I would suggest you spend that time learning Eminor,and why Hammett plays the solo the way he does as opposed to how.I'm pretty sure the whole solo is a mish-mash of Em pentatonic minor and Eminor melodic minor,learn those scales all over the fretboard and almost any Metallica song is within your reach.