Here is what I did and it worked on this end.
I told my son that he had 30 min. to clean his room. Anything left would be gone to Goodwill. After 30 min. I came in with trash bags and boxes. I made him pack it up. Then we took it to Goodwill. (I cried inside at all the money lost). But this didn't work!!!
The next time he wouldn't clean his room he lost his room. I took everything out. Including the bed. He had a pallet on the floor and was allowed to keep his teddy bear and a book. Everything else went to storage. After two days I gave him back the bed, after 3 days he got one box back. I got a shoe holder that held shoe boxes. I got plastic shoe box bins from the dollar store. I made sure that every toy in the box had a place. We labeled the boxes so he would know where everything went. As time went on he would get a box back and get a labeled plastic bin to put it in. He now has all his toys back and labeled plastic bins to put them in and he keeps his room clean.
Oh- we also got rid of the laundry hamper. He now has to take his dirty close directly to the laundry room. This has helped with missing dirty clothes.
We figured out with him that he was overwhelmed. He needed structure. He needed to know what went where. With labeling the plastic bins he no longer seems lost when cleaning his room and he can't use the "mom can you help me, I don't know where this goes".
We used generic labels (i.e games, cars, McD toys, Misc, Electronics, plastic men, legos etc) and some bins have the same label. That way if one gets full he just moves to the next one. I don't check to make sure that the right thing is in the right box. I highly doubt they are, but the fact is he keeps his room clean.
We also have a new rule. If you get something new and don't have room in your plastic bins you have to get rid of old toys to make space for the new toys. I let him choose what he wants to give to Goodwill and what goes in the trash.