yes

yes means yes

do you want icecream.
yes

Yes'nt

Person 1: Do you want Icecream.
Person 2: No I don't want Icecream.
But you can also say

"Yes'nt I want icecream.
Means No I don't want icecream.

Yes'nt I want icecream.
I yes'nt want icecream.