I did try to unwrap my model in blender unfurtentally my model is from a scanner which makes the tipology a bit triky which makes it harder to texture it... this is why i try to do it in photoshop.
Thank you for your advice but I'm not sure it will help in this case.
Will appreciate any other thought though...
Then download the demo of 3DCoat and retopologise your model by rebuilding a mesh on top of your scan data or use the tools in whatever 3D tool you have. Even Blender has okay-ish tools for that. Trying to create a UV set from a non-contiguous mesh isn't going to work since all polygons will have the same UV range, give or take differences in orientation and perhaps a few auto-welded UV islands. Fixing this manually will take days and weeks. You really can't put off the unavoidable.
Mylenium