Hi croftsylvia & a big welcome to Rootschat
The Cemetery Office should have given you a Section number & a Grave number, you will need both.
If they did what were they? from it we can tell where about in the cemetery the grave should be.
As Celia said they might not have a stone. It's unlikely that if they did, it's been removed, if badly unsafe it would have been Laid down, or given a stake to support it.
Let us know if we can help further.
If the grave is unmarked (ie no headstone) the cemetery office should

if asked nicely put a marker on grave so you can find it when you visit, so try them again if you can
Regards