Hi @Rys,
Thank you for your question about fixing your sunken pavers.
They have sunken because the substrate has eroded and the base material has washed away. To fix this issue, you will have to lift the pavers, reinstate the base and then relay the pavers.
I would suggest lifting the pavers, adding road base, compacting it with a tamper, then relaying the pavers, checking they are level with the surrounding pavers with a spirit level. Small adjustments can be made by tapping the pavers with a heavy rubber mallet such as this Craftright 32oz Rubber Mallet.
Once the pavers have been reinstated, sweep polymeric paving sand between the pavers and wet them down to activate the bonding agent and lock the pavers in place.
Let me know what you think and if you any further questions, please don't hesitate to ask.
Jacob
