If you could tell me what textures you're missing, I could restore them for you by giving you the original textures. In future it would be useful if you create a back up for the textures so you don't lose them and stress out.
Or when you are putting things like (for example) grass textures into your texture folder and it asks you to replace them, try not replacing them. Again, tell me what textures you're wanting and I'll send them to you.