my bike brakes are f*ck*d

i dont comment it, but i like ride a bike, and princpaly in hostil ambients, but my grandfather told that the brakes of my bike (that is for mountain) ARE FCKED, I DONT USE IT IN 1 YEAR, I USE IT 2 WEEKS, AND THE BRAKES DONT WORK, what the hell with my life. i ask in a place where they repair bikes and ALL THE KIT OF REPLACE THE BRAKES COST 17$ DOLLARS. the funeral is cheaper