Hi A.,
If you can stand one more bit of advice, here's mine. I agree with the other moms that your son probably isn't ready to potty train, but I'll bet you're not thrilled having two in diapers, either. When you do decide to make another go of it, here's what we did.
We decided to train our son a few months before his third birthday, even though he wasn't showing interest or readiness, because we were going on vacation overseas and did not want to have to take 2 weeks worth of diapers with us. First, we got him a smally potty chair and kept it in our bathroom next to the toilet. He always followed us into the bathroom, so the chair was there for him to play with whenever mommy and daddy went. This particular chair played "Twinkle, Twinkle Little Star" when there was enough liquid in it to cover both of the contacts, so we would let him pour water into it so he could make the music play. He loved this!
About two months before we left, we got a book called "Toilet Training in Less Than a Day" by Nathan H. Azrin, Ph. D. and Richard M. Foxx Ph.D. They developed a learning method for teaching developmentally disabled children to use the toilet. I was amazed at at how well the method worked and how easy it was.
Step one of the method involves getting a doll that pees and making it wet its pants. You then tell your child "Oh oh! The dolly had an accident and needs to practice changing his wet clothes. Let's help him practice." You then help your child change the doll's wet clothes for dry ones, 10 times in a row.
Even though the book doesn't say to do this next step, we then added in showing our son that "dolly" could use the potty instead, and that when he did, he didn't have to practice. We made the doll go in the potty chair, which of course, made the music play, which our son thought was hysterical.
The actual step two has you lock yourself in the bathroom with your child, a bunch of favorite salty snacks and a lot of your child's favorite drinks. You put your child in underwear and easy to pull off shorts, and have the room well stocked with books, toys, several clean changes of clothes and some cleaning supplies. Feed him the salty snacks, which makes him want to drink a lot. Ask him every 15 minutes if he has to pee and encourage him to use the potty. If he uses the potty, Great! If he has an accident, you say "Uh oh -- you had an accident, just like the dolly did. Remember how the dolly had to practice changing his wet clothes? Well that's what we're going to do now!" Then you have him practice changing the wet clothes, 10 times in a row -- just like the doll. Keep up with the snacks and drinks. After a no more than a couple of rounds of this, he will begin to recognize when he needs to use the potty and will hopefully prefer to use it over having to practice changing his wet clothes.
The first time your son actually uses the potty, make it a BIG achievement with tons of praise, hugs, kisses, and maybe even a special prize. But, stay in the bathroom and continue the process for at least two more rounds. By the end of the day, he will have gotten the idea of what the potty is for and how to use it.
Expect accidents on occasion (and possibly at night) for a while, but he's not likely to have many. I think our son had a couple during the first week after training, and then almost none after that. We kept him in diapers at night for another 6 months, until he was waking up dry in the morning on a regular basis, then moved to training pants and rubber sheets. Since we made him practice the clean up when he wet the bed, too, night time accidents didn't last very long.
BTW, every child is different. We tried this method with our daughter a few years later at about the same age and she just refused to use the potty (she actually liked cleaning her clothes and the floor!). We waited 3 months and tried again. The second time around, it worked like a charm!
Good luck. When the time is right for your son, you'll know it.