Watch this video from This Old House to learn how to repair a brick patio.
1 Use a flat bar to pry all the full-size bricks from the sunken area of the patio.
2 Number each cut brick removed from the edge of the patio using a crayon.
3 Dig out sodden clay or soft mud from the patio with a pointed trowel.
4 Use a 4-foot level to determine the finished height of the brick.
5 Fill depressions in the sand bed with ground limestone.
6 Use a hand tamper to compact the limestone.
7 Add 1 inch of sand, then check with the level to ensure there's a 3-inch space for the bricks.
8 Set bricks back into place, tapping each one down with a rubber mallet.
9 Sweep fine-grain sand into the joints between the bricks.
10 After the first heavy rainfall, sweep more sand across patio to fill voids between bricks.