Brush the crack with a wire brush to remove any loose particles. Break up loose mortar with a chisel and remove it.
Wet the inside of the crack using a garden hose. This will help the mortar set and will ensure that the surface is clean and free of dust.
Press mortar into the crack using a jointing tool. Use the jointing too to make the rounded swipe to match the mortar between the other bricks.
Wipe away the excess mortar with a trowel.
Break up the mortar surrounding the broken brick so the brick will come out easier. Use a hammer and a chisel to chip away at the mortar until it is essentially gone. Remove all of the broken brick.
Brush the inside of the hole with a wire brush and blow the hole with compressed air.
Wet the inside area with a garden hose.
Apply mortar on all four sides of the hole with a trowel. Pack the mortar in tight by pressing the trowel against the mortar.
Push a new brick into place and scrape away any excess mortar with a trowel.
Shape the mortar surrounding the brick by running a jointing tool into the crevices.