Teaching to fetch?

You could teach a toy obsession.  You use one toy or maybe 2.  That is his special toy.  Keep it up on a high shelf where he cant get to it.  Everyday, maybe 2 or 3 times a day take the toy down and play with it in front of him.  Cuddle it, toss it in the air, put it near your mouth(or in if you can stomach that).  Make all kinds of excited noises, and generally make the neighbors think you are crazy.  And then put it back on the shelf.  Once he gets super excited about that toy, let him have it for a second.  Play tug with it, or let him fight it, always with you intereacting, never on his own.  Then put it back up on its shelf(hint:make sure he can always see it).  Once the toy is his favorite, you can toss it a little ways, maybe 2 feet.  Where you can still reach it if he doesnt graab it a bring it back for some play.  Gradually increase the distance.  I have seen this work well enough that the retrieval instinct becomes so strong you can switch to any toy and the game becomes fetch instead of playing with special toy.

Fetching can take time to teach because you are asking your dog to perform a series of behaviours:

1. Chase the item
2. Pick it up
3. Hold the item
4. Carry it
5. Come back to you with it
6. Give it back when you ask for it

With dogs that aren't natural retrievers, you should probably break the retrieve into steps. First, get them to willingly take something from you. If your dog is having problems, start with treats. Offer your dog a treat and say "take it" - do that until she is willingly opening her mouth when you say "take it".
Then choose something that she likes to retrieve - a lot of dogs seem to do well with sticks but it can be anything the like to play with. Then practice the "take it" with that item - some dogs need help so you might have to gently open your dog's mouth and pop in the toy. Gently keep her mouth closed over the item for a couple of seconds, while you praise - then say "give" and treat her.
You can move onto holding it when she is willingly taking the item. Getting her to hold it is usually the most difficult part...at first you will delay asking her to "give" for a few seconds and say "hold it". When her jaw starts to open, you will gently put your hands over her mouth and say "hold it" then praise and reward after 5 seconds.
Once you can get her to hold it for 30 seconds you can work on her moving towards taking the item - have her reach for the stick instead of you offering it to her...at first just have it a few inches away from her nose, then you can start lowering it towards the ground or having her take a couple of steps in order to take the item.
When she is reaching for the stick, you should work on having her hold the stick while walking..go slowly and reward her often. If she drops the item, go back to having her hold the item without moving.
The final step before putting it all together is to teach her to pick the item up off the floor...at first hold the item above the floor, eventually letting just one side of the object touch the floor while you hold the other end up...
Then you are ready to put the whole process together!! For dogs that aren't natural retrievers, it can take weeks to teach but it shouldn't take that long if you are consistent with her!
The first few time you put the whole fetch process together, it's best if you have her on-leash so you can reel her in as a reminder that she is suppose to bring back the item.