How to delete a duplicated song in your music app?

Okay I have an iPhone 4S and I want to probably delete every song in my library and playlist because I accidentally sync my iPhone at an earlier version with my old songs and now it is on my iPhone. And it is undeletable even if I tap and slide it to the right! So show me the steps please!

Well, the only way i know how to do this is if you sync it to your itunes. From Itunes, you go to your library of all your music. Then on the tool bar of itunes click "View" then "Show Duplicate Items".it then should show up all the items that are duplicates in your library.

Follow these steps:

1.In iTunes, select File and then click on Display Duplicates. This will show you duplicates with a matching song title and artist name

2. If you want to see exact duplicates only, hold down the Alt (Windows) or the Options (Mac) key and select Display Exact Duplicates

If you are not satisfied with the results, I recommend you check out Easy Duplicate Finder. It's a really cool program for finding duplicate songs because it can compare them by content. And it can sync your iTunes plus delete invalid track references.