Paver patio steps can suffer damage from excess settlement, tree root incursion, and repeated impacts. The amount of damage that has been done and the way the steps have been built will dictate how the repair should be completed.
Generally, the repairs are more tedious than difficult and can require a bit of muscle.
Step 1 - Examine the Damage
In this case, the paver step has been created with a front retaining riser and pavers arranged behind the riser and the retaining riser of the next step up. The riser is in good condition, but the pavers have been displaced by some sort of subsidence.
Step 2 - Remove the Pavers
If the pavers have simply been laid on a sand bed it should be possible to lift them out using a pry bar. Press the pry bar between the two pavers that appear loosest and try to raise one of them. Once the first is removed, the rest should simply lift out.
Step 3 - Check the Pavers
Hopefully, the pavers will be in good condition and can be replaced. Clean off as much of the dirt as possible to check for any cracks that could get worse over time. Replace any unsatisfactory pavers.
Step 4 - Dig out the Sand That was Under The Pavers
Look for any reasons for the settlement that caused the pavers to subside. There will be a cause so don’t fail to do this. Often this sort of subsidence is caused by a leaking pipe creating a waterlogged area that can no longer support the load it had.
Not so often the damage can be caused by small animals burrowing under the steps and undermining them.
Step 5 - Repair the Cause
Before you can mend the steps you must mend the cause of the collapse to prevent it from happening again.
Step 6 - Build up the Step
Once the repair is finished, refill the void under the step and then cover it with leveling sand. Lay a paver on the sand at one end of the step and tap it down with a rubber mallet. Make sure it is horizontal and level with the riser.
Replace the rest of the pavers leaving a gap of about half an inch between them. Tap each paver home firmly so they don't rock or wobble.
Step 7 - Apply Sand
Pour sand over the pavers and sweep it into the gaps between them.
Wash the sand in with a little water from a hose. This will also help to clean the pavers a little. Keep adding sand until the gaps between the pavers are filled. This is a straightforward repair.
If the pavers had been installed with concrete, removing them would have been much more difficult and some of them could have been damaged while trying to remove the concrete from them. It is also possible that the retaining riser could have been damaged as well, creating a much more complex repair.