Really, really really NEED help!!!

My cat has abbandoned one of her kittens. We have already lost 2 due to complications and this one is going the same way.

I found him laid on his own and moved him using the towel inside the box. He just laid when I moved him to, didn't move himself, just laid there. I rang my mom and she told me to leave him but with how he's been acting I knew he wouldn't survive. He is 2 weeks old on Monday. He's still really lifeless. He's a lot warmer than before (When i took him out of the box he was stone cold, now he's much warmer). Ive tried to give him milk via a suringe but he doesnt really accept it. It does go down his throat though.

Hes very sleepy right now and ive wraped him up and got him in my arms.

What shall I do?

He needs to warm up. And don't feed him until he's warm; he can't digest when he's cold and the milk will sour in his tummy. Once he's warm, you can feed him. . .here's a good website with info on how much to feed and all that: http://www.kittenrescue.org/pages.php?pageid=15

Agreed. Just keep warming him as much as you can. Once he's warmed up and get's some food in his belly put his box somewhere warmer with lots of blankets/towels. You can even make up a rice sock (just put uncooked rice in a sock and heat it in the microwave) and put that next to him. Just make sure he has room to move away from it if he gets too warm. 

Is it possible to try and put him back with Mom? If not, then he's going to need to be fed every two hours and stimulated to go to the bathroom. There are a lot of links on how to do that on the link Willowy posted and also on the general links here: http://www.thecatsite.com/t/74659/welcome-message-important-kitten-care-links

Good luck and thank you for doing all that you can for him! 

Do you know why mum left the kittens? Was she in a small confined space so she could just be with them without stress?

Most kittens will fight the syringe or bottle at first, and you do need to take care not to flood the lungs. As said he won't eat if he's not warm enough.