Go to the Sears web site type in the numbers on the id plate under your seat.
Sears will allow you to download an owners manual & the parts manual.
Illingine has correctly identified the broken part.
It is the brake actuating lever ( not bracket ) and you will find the rest of it on the end of the brake rod.
Lay under the mower, and get some one to work the brake lever.
Follow the moving rod and on the end you will see the remains of the lever and some springs.
Take a few photos before you take it apart
Blow down the area before you start to pull things apart.
The lever is held on by the single bolt in the middle down the bottom
When you remove the brake lever there are two pins behind ir which actually push on the brake pad and they will either be rusted in solid, or fall out & get lost.
There is no repair manual available for you mower because Sears want you to use their technicians.
However all of them work the same and there are manuals available for other mowers.