I adopt only older dogs and many of them had absolutely no interest in playing with toys of any kind.
But one thing they all were able to learn and to love was "find the treat". If they were able and willing to sit/stay, I start off by waving an awesome treat (steak or liver or something the dog really wants) in front of his nose and then quickly walk just a short distance (1-2 steps for a small dog, 3-4 steps for a larger dog) and drop the treat where it was very visible to the dog. I then return to the dog and say something like "Find It" in a happy, excited voice. (The dog wont know what "Find It" means but, over the course of time and repetition, will learn to associate those words, or whatever words you use consistently, with finding and eating a treat.)
If the dog doesnt know how to sit/stay or is too old to sit comfortably, he can stand or lie down and someone should hold him by the collar. And the placing of the treat should be done quickly so the dog doesnt lose interest.
I gradually extend the distance that I walk to drop the treat, still in sight of the dog. Then I start letting the dog see me place the treat underneath a corner of a rug or a towel on the floor. The idea, at this point, is that the dog doesnt have to work hard to get the treat -- so it should be very close to the edge of the rug/towel/etc.
Then I walk to the adjoining room or hallway and drop the treat in plain sight very close to the doorway (so the dog can see it easily once he gets into that room or hallway). Eventually I progress to placing the treat underneath a rug/towel/etc in that adjoining room.
I progress to the point where I could hide the treat in another room, maybe even several rooms away, and the dog can find the hidden treat (always hidden on the floor or underneath something on the floor). Once the dog is confident, I hide the treat in more difficult places.
Some considerations: Dont be tempted to progress too quickly. Extending the distance and hiding the treat should take a long time – maybe weeks. The dog must be confident that there will always be a treat and that it will be fairly easy to find at first. With the hidden treat, the dog will learn to use his nose once the treat is hidden in an adjoining room or hallway. Dont progress until you can see that the dog is using his nose -- you can encourage him in the beginning but you should phase out the encouragement ("Where is it? Can you find it?") if you see that the dog is becoming too dependent on it.
Eventually I can end up hiding the treat several rooms away. It feels so good to see the dog just know that there's a treat hidden somewhere and go confidently from one room to the next looking for it. And, of course, he gets a lot of praise when he finds it.
This can be good exercise for smaller dogs. (I have to be careful to reduce the amount of dog food they get when playing this game or the exercise may not offset the calories in the treats.)
I've adopted some older (8-9 years old) dogs who, sadly, had no idea of play -- but they all were able to learn to love this game as long as I didnt submit to the temptation to progress too fast. Of course, it also helps if the dog is somewhat hungry at the time and if the treat is something too yummy to pass up.