There's so many factors that can result in fret buzz; poor set up, high frets, wonky neck, wrong neck angle, action too low etc. All are pretty much easy to solve.
If you're impartial to a bit of sweary media content, fire up You Tube and watch some of Milehouse Studio content from Paul Richards. He's done a series of videos fundamentally about turning around (unloved/bedroom player) guitars into decent playable instruments, using budget tools/gadgets.
He makes no bones about the fact that he wants to entertain people 'while they're on the toilet at work' and regardless of the fact that his vernacular and delivery is very amusing, there's a ton of sound content in these videos; it's a lot easier absorbing these than reading how to do stuff.