How can I deal with my son who is answering back any time I try to explain he is wrong, he is not responsible for his belongings, that he has to help me as is only him and me?

Nine is a good age to reason with..

I would first find out if there is anything in his life that he is worried about or upset about.

Then if its just the two of you there,it means you're the bad guy and the good guy.

Depending on the type of kid he is.. example,I have a really good kid,and a hound of a child who would not pick up a sock! Without an argument.

Sit him down and explain that you don't want to give out all the time,but if he does not pick up his stuff you will remind him once,and then you will put it in the bin... and stick to that!

I only had to do it once.

You could also take away prilivages... again give him a chance to do it and remind him nicely what will happen if he does not.. no TV,etc...

Kids need to know where the boundries are,and its up to you to set them and keep them...

You could also affer him a reward if he does it for a week,example a trip to the cinema,or a friend over,don't fall into the trap of rewarding everything.. 9 year olds will take advantage...

Another thing you can do is set his chores,and offer a small amount of money for extra chores,is there something he really wants,if he can raise half the money you'll chip in the rest...

These are just some ideas... others will post with more.

Thanks for your aswer. Let me tell you that Nicholas my son and I are from Argentina, we have moved to the States 7 months ago and I know how hard it is for both but I see that he really enjoys so much of living here, he wanted to start playing football (American not soccer as is the one common in my country) and I supported him, 3 times a week rushing to drive him to practise , Saturdays games, he knows he counts with me but whenever he lose from glasses to jackets and his answer is" I don't know where I left it" I got mad at him. I explained in all kind of ways that I am the only one supporting and working for us. I have being alone for ore tha 9 years, he has never seen me with a man, I do not go out, only work and the rest at home and with him.
Of course I punish him and for more than a month we didn't go out at weekends nor movies, nor any other place he likes, nor friends at home but he looks as he doesn't matters, he replies to me very hironically.
Sometimes I cry so much,I feel he doesn't love me. What can I do, I never married but I do not have any contact with his biological father since he is an addict and he used to sell drugs. When I realised I decided that it is not what I wanted for my son and for me. Anyway it suffered from that situation so much that I didn't even have a date.
I don't feel I am a bad mom I do as much as I can but it is not enough. I am so down for this

It must be very, very hard to raise a child on your own. Not only do you have to work, go to games, cook, clean and support on your own but mostly you have no time for you. You are a great mom for not introducing so many men... waiting for the right man to step in for you and your son rather then dating and confusing your child... I really admire that! I know a lot of divorcee's and I feel really sorry for the kids because in the divorcee's I know the children are usually on the back burner as the adults seek their own happiness in relationships that usually end up fruitless. So, that isn't your issue, what may be a small problem is that you give so much attention and haven't set down boundaries for him before. In all probability you have picked up and done a lot for your son and so the introduction of additional responsibility and encouragement of independence may be a challenge. He is so use to you mothering him and doing things for him.

Not abnormal, very normal and it will take firm discipline but plenty of love. The suggestions Redhead said are fantastic and I completely agree that you should refrain from using bribery to have things done! Bribery is effective but then you have a bigger issue... he won't do anything without a reward! So, start the chore list (for allowance), do the star chart (in support - make it big and colorful) and begin the allowance (Teaches the child money doesn't grow from trees and it must be earned by introducing responsibility - transitional... eventually make it a normal thing). At the end of each week he has earned his allowance or whatever it is that he would like (to a certain dollar amount - for the chores incomplete then a certain deduction should be made). Of course there will be things on the chore list but there will also be things that are considered "Rules" and each rule if broken has a penalty (kind of like the Bernstein Bears Book - Manners) and those should be suspension of "privileges". Keep the chore list to introduce the concept of earning money and responsibility but keep the rules separate and apart on a list - as a suspension of what he already has. Keep the love and compassion very much there but also stay very firm.