It is possible to obtain non-zero padding fft from zero padding fft? This is just a question out of my curiosity, normally we do not do this
I have a x(n)=[1 2 3]

y(n) = fft[1 2 3 0] =  6 + 0i  -2 - 2i   2 + 0i  -2 + 2i %zero padding
y'(n) = fft([1 2 3]) = 6 + 0i  -1.5 + 0.87i  -1.5 - 0.87i


I used Matlab to generate these results.
My question is there way to obtain y'(n) from y(n)?
Yes. Zero padding allows interpolation in the frequency domain. You can get the same result directly in the frequency domain using circular sin(x)/x interpolation. See for example
http://en.wikipedia.org/wiki/Whittaker%E2%80%93Shannon_interpolation_formula