No content in my music library on my iPhone?

All my music is still on itunes on the computer, but even after I take it out and plug it in again, the phone syncs and then when I try to play a song it doesn't play and an exclamation point appears next to the song name. All my songs are still in my computer as well, so I haven't deleted them or anything.

Help please! Thanks so much.

Added (1). Hi, I just added a new song to my iPhone, I can now play only that song on iTunes and it has come up on my iPhone. But only that one.

How can I locate my other songs please?

Added (2). Hi, I just added a new song to my iPhone, I can now play only that song on iTunes and it has come up on my iPhone. But only that one.

How can I locate my other songs please?

Added (3). Hi, I just added a new song to my iPhone, I can now play only that song on iTunes and it has come up on my iPhone. But only that one.

How can I locate my other songs please?

You should put new song in your iphone

Are you seeing the exclamation point on your phone or on iTunes?

If its just on your phone and not on iTunes then connect it and wait for the name of your iphone to appear in the left panel. Click on it and you should see your phone info and tabs at the top. Click on the music tab. Uncheck the option to "sync music" and choose apply. Once it's finished syncing, check it again to sync all your music back and hopefully that fixes the problem.

If you're seeing the exclamation point next to the songs on iTunes, then double tap a song to attempt to play it and it should say that the file could not be found or something along those lines. It should also give you the option to locate the file. Choose this option and find the song on your computer.