Cracked Lose slab help ?

[kingrollo]

Easiest way to repair this cracked/slab step. And how to identify replacement slab ?

 

[oxoman]

Easiest way to repair this cracked/slab step. And how to identify replacement slab ?

View attachment 814917

If its the same as the new one on the left, then I suspect its a standard concrete riven pattern available from B&Q. Personally I'd smash the broken one up to remove it and whatever its been bedded down with. Normally a mortar mix. Get new mortar mix it up and do 4 or 5 big dabs then mount new slab on top. Make sure enough under the new slab for it to compress down so you can level it. It's not mortared joints so should be easy enough. It's possible that the broken slab has been bedded down on sharp sand so thats another way to do it. Eitherway no more than a £15.00 diy fix.