when my dad was riding my bike, some guy came up to him and changed the gears so it would be easier for him. now when i ride it, max is easy. how do i change the gears back so they are hard again?
Just guessing at your bike's configuration. There are pairs small levers on the left and right sides of the handlebar, near the hand grips. There are usually two levers on each side. Push the bigger lever on the left side and see what happens.