[Keith]

I have a Schwinn High Plains and the rear brakes fell off on a trail. Pretty much the entire setup including the brackets.

How can I replace it?

 

[Grape Ape]

You have any pics of the damage?

 

[hophead]

I have a Schwinn High Plains and the rear brakes fell off on a trail. Pretty much the entire setup including the brackets.

How can I replace it?

Is it a v-brake...

or cantilever?

Either way the arms are secured to bosses on the seat stays with two bolts.

Park Tool Website