First thing is to have some pateints.second practice saying abc's with him. You have to realize he is having some difficultyso take your time with him. Let your other two children read short stories to him. But most of all please donot make him feel like he is an out cast.

Has your son's teacher suggested an "IEP" --individualized education plan? It seems like you need to get a team together to help you and your son on a more successful path.  Make an appointment with the teacher and the school counselor first.  A specific evaluation would be helpful so you'll know just what challenges your son faces and the best way to address them.  ...Ask for an "IEP"--for him so you can help him in the most helpful way!

my 5 year old can't read and don't know her abc that well either.your son is not the only one.

As a parent, i was in same situation 3 months ago . my son is 4 year and 6 months. i couldn't count and coundn't do his abc.i was so frustrated. now he can do his 1 to 10.because he learns cursive writing in his school.(they don't teach them in order) he does c,a,d,g,q,o,l,m,n,u,v,.......and all i think you son needs more time to learn. start with numbers. do one number per  day. give him more time to know the number. when he watches tv,show him tv remote,ask him to find the numbers on remote.and you can do same thing by using calculators,mobile,or even computer.open a wordpad. ask him to press that button for numbers/letters.make it fun way.if he do his numbers ,then tell him that you are very pleased with him.bribe him.spoil him.all the vey best.

It takes time but he needs you to work with him every day.  It can get frustrating but bite your tongue and remember you are helping him lay very important ground work.  We went thru similar problems and I made the choice to help my son every single day with books I bought at Wal-Mart etc. and as time has gone on and we have made huge improvement now we have moved up to the Didj (eductional toy), Leap Frog has some great tools!  Some DVD's you might look for is the Leap Frog Letter Factory and Talking Words.  We started and I was scared I didn't know what I was doing but when it clicked for both of us he began to improve in an unbelievable way!  Once they get their self esteem improves and then it all follows.  We started making progress and then were so proud of ourselves I can't describe.  We consider ourselves a team.  I also had to realize where I had difficulties when I was in school and I am determined to help my son not have the same difficulties.  You may feel like you are not as capable as the teachers but you will find you are because you can motivate your child better than anyone.  You can use humor, stories get up in the floor and do the craziest "A" dance you can come up with and have him write an A.  What ever your style is you can work it into your study time- have your other children help they can play teacher or teachers helper.  That kind of thing- you can do this!  We had a rough Kindergarten but have turned it around for a very successful 1st grade.