Hook on bobbin hitting scarf of needle
 

Bumped the needle when sewing and now the hook on the bobbin is touching the scarf on the back of the needle every time it goes around. Breaks the needle when sewing. How do I adjust either bobbin, or hook or needle to stop tapping the back of the needle?

1. Is the needle bent? You've already tried another?
2 - Is the needle seated up as high as possible in the needlebar? Is it screwed in very tightly?
3 - Is the needle a sharp or ball-point and not one of the Singer "stretch" needles? (stretch refers to the needle, not to the fabric it is supposed to sew.)
4 - Is the needle positively the correct one for your machine? Some machines require different needles than the standard 15x1.

If you have an industrial machine, that might be what is suppose to happen, but they also don't take the same needle that most domestic machines take.

It's possible that the needle got bumped because the timing shifted, not the other way around, and sometimes it's both. Like if you were sewing something very thick and the needle got pulled an hit the needle plate instead of going down the hole, and the pressure caused the needle bar to slip and now the timing is off too.

Yep, that sounds like a timing issue. Not something most people can fix ar home.

What model of machine do you have?

It sure does sound like a timing issue. Some are easy to fix others require the machine to go into the shop for repair. Most machines made in the last 20 or so years need to go into the shop. Even on the majority of my older machines I am not confident enough to play with the timing so I take it into the shop.