I can't sync my iPhone with the music on my laptop

When you say nothing changes, what exactly do you mean. You don't see anything happen on the iPhone? Do you see an error in iTunes? Once you select more music, are you syncing? Is it possible that you are using Manually Manage Music?

You may need to try to explain each step you are taking here to determine where things are going wrong. Do you have the latest version of iTunes? What computer operating system are you using? Is this music you are trying to add in your iTunes library?

Why not? What happens when you try?