I have an existing front walkway which is approx. 20 feet long. The problem is, the walkway is made of random sized squared off slate pieces which have loosened up causing a hazardous situation for anyone visiting my home. The slate is set on concrete. What options do I have to replace this walkway, that will not cost too much money? I had a thought, would the existing slate pieces be able to be used much like pavers, which are set in sand? If so, what might something like that cost?
Would appreciate any suggestions. Thanks!

A stone walkway should be pieces at least an inch or so thick. Yours might be thinner which is why they chose to lay them in concrete. You could lay slate directly in the ground or on something called paver base which is stone dust finer than ordinary gravel. Sand is easy because you can scoop it away to level out any unevenness. But it tends to get tracked around or stolen by ants. Slate is top of the line for stone walkways the pieces are big, flat as a chalkboard and there's a choice of attractive colors. (The local stones at my place are more like bowling balls.) You would still have to deal with the concrete underneath anyway. If you can lift the loose pieces and sweep any loose dust or cement away you might be able to use some kind of tile adhesive to make small repairs. It comes in a can like paint or in a tube you can squirt out of a caulking gun. Would need a waterproof formula.