Paver Sand
 

My Paver Patio paver are starting to sink in on some areas. My question is this, what type of sand should you use to level up the paver stones?

I believe I have seen sand identified as "Paver Sand" at Lowe's.

IMHO, you should check to see why the existing sand washed away or sank, look for irrigation leaks, problems with runoff or gutters, etc. If you find any of these, repair these first, then add sand, be sure to compact the sand, and replace the pavers.