B.B.
My suggestion is to get bins to sort the toys into. This works for me in my toddler classroom. You could also put a picture on the outside of the bin if you wanted to so he would know which bin the toys go into. Also make sure you don't have a ton of toys. You could take some and put them away and then you could rotate the toys when he seems to be getting bored with the toys that are out. My second suggestion is to make sure after he dumps a bin and is done playing with it, you don't let him move on to dump more until he picks up the first batch of toys. You will have to sit there with him and maybe even help him but don't give in, insist he cleans up and give him lots of praise when he does. Consistancy is the key. I hope this helps. Let us know how everything goes.