Just get it really fat until it realises it hates food and the only thing that will satisfy are toys.

^ You horrible *&@%#!

Do what veb said.
Lol, my dog has never liked toys.

Slap it with the toys until it gets angry and bites back, then guard yourself with the toy.

Repetedly insert all cucumber shaped toys into its asshole. Once it realises what is going on and yelps in protest shove a toy in its mouth.

uh huh..
Thanks guys... I guess?

But uhh, How long will it tak for an older dog (4 yrs) to get used to this dog.
In case it might be useful to know, the 4 year old dog is a golden retriever.

If you can, try to pet them, or be with both of them at the same time, rather than just 1, the older dog might feel it's being replaced.

give him ur mom's favriot shoes

use the ideal from Marley.When he comes too close kick him in that "special place"

When it bites you shove the toy in his mouth or changes it's attention

My dog is 5 years old and WON'T play with anything.
He just jumps on the couch and sleeps all day.
If he's outside he goes behind the kennel and lies there.

You should do something before your dog ends up becoming like mine.