1st and foremost, why did you need to change your ear speaker? What happened? Was the old ear speaker working at all before?
2nd, to get you started, and if you were not hearing any sound to begin with, may be the ear speaker mesh is dirty. Poke 2~3 holes in the middle of the mesh using a fine needle. Do not insert it more than ~1 mm. If you start hearing better, then you need to replace the mesh, not the ear speaker (or leave it like this now that it's working). Try this and let me know.
3rd, it could be that the part you used is defective, or you received the wrong part. Where did you get it from? Does it look exactly like the ear piece you removed?