I want to put a texture on a special part of a sphere. I do not know how to do this.
Can anybody help
You’d need to unwrap the sphere’s UV’s, put this “special part” in an area by itself, and apply your texture to it.
This isn’t something Unity does- so your question isn’t really relevant to this site. You’d do this in your 3D modeling program.
First of all- welcome to UA, don’t post comments as answers. 
And if that’s what you’re trying to do, you’re probably going to need to manipulate the UVs at runtime using the mesh class. I’m not sure what your skill level is, but if you’re a beginner, it’s not going to be an easy thing to do.
I stand by my original answer- if you need to change the position of the texture on the sphere, you could actually animate the UVs however you needed to- it would just require a little bit of forethought and planning on your part.
If that doesn’t help you out- you may need to explain in detail what you’re trying to do. There’s a possibility that you’re going about something the wrong way.
but I want to do it in unity,I do not want it to be fixed.the texture and its position on sphere maybe be changed during the play mode( with some actions). is’nt there any way to do this?
Thanks for answer