Hot to restore music in iPhone using iTunes?

So I downloaded music on my computer then put them on iTunes then plugged my phone in and out it onto iTunes of my iPhone 5. Now I plugged my phone in, and deleted all the songs in my phone, I had 100 + songs but when I look on my phone from the computer it shows them all but if you press on some of them, it gets a little "!" sign next to it. But on the phone it only shows 40 of them.

If you got the! In the circle sounds like iTunes the link has broken. This can be down to the files being moved by accident the phone has deleted them as they are no longer available when you plugged it in again. You either have to just find one song of your computer via my docs or click on the unplayable song and locate it both ways are similar but if other songs are in the same place all will be restored. Both of these methods should should fix the! And they will go Back on the phone hopes this helps