Who sings "sir i wanna buy these shoes" i know newsong,there is a version with a little boy singing too.who???

It sounds like you're talking about "The Christmas Shoes". The Christian group NewSong sings it. Damn depressing song, too. I've never heard the version of a little boy singing, but I'm pretty sure that towards the end of the NewSong version, kids start singing the lyrics.

Lyrics:

It was almost Christmas time, there I stood in another line
Tryin' to buy that last gift or two, not really in the Christmas mood
Standing right in front of me was a little boy waiting anxiously
Pacing round like little boys do, and in his hands he held a pair of shoes
His clothes were worn and old
He was dirty from head to toe
And when it came his time to pay
I couldn't believe what I heard him say

CHORUS:
Sir, I want to buy these shoes for my mama, please
It's Christmas Eve and these shoes are just her size
Could you hurry, sir, Daddy said there's not much time
You see, she's been sick for quite a while
And I know these shoes would make her smile
And I want her to look beautiful if mama meets Jesus tonight

He counted pennies for what seemed like years
Then the cashier said, "Son, there's not enough here"
He searched his pockets frantically, then he turned and he looked at me
He said, "Mama made Christmas good at our house,
Through most years she did without
Tell me, sir, what am I going to do,
Somehow, I've got to buy her these Christmas shoes."
So I laid the money down
I just had to help him out
I'll never forget the look on his face
When he turned to me and said, "Mama's gonna look so great."

CHORUS

I knew I'd caught a glimpse of heaven's love as he thanked me and ran out
I knew that God had sent that little boy
To remind me what Christmas is all about

CHORUS

I believe that the "young voice" is on the newsong version.