iTunes may sometimes fail to locate one of your music files when you try to play them and an exclamation mark will appear right next to the song that appears to be missing.
Such an issue is known to occur after any major software update or after a system restore from backup or if the file's source drive is disconnected from the computer. Any root level changes to the computer's filesystem or registry could remove all file associations for the iTunes library and hence the app will be unable to find the music file.
In such a scenario, you could first try redirecting iTunes to the source location of the file. For instance, you may have moved the file to a new folder or renamed the original file wherein you can simply point iTunes to this folder to fix the problem.
Here is how you do it:
- Double-click on the missing song in iTunes
- Hit the blue Locate button in the ensuing pop-up window
- Now manually search for the music file linked to the song you are trying to play by using the Finder window
- Just browse through the folders where you usually store the music files and then click Open button
- iTunes should be able to play the song after creating a file association with it
- If the issue persists, ensure that you have physically connected the source drive to the computer from where you are trying to access the music file
- On the contrary, a recent backup may have data errors and the same could be rewritten to the hard disk during a restore process. In such a scenario, you need to re-download the file or re-import them via CD/DVD or external USB drive.
If the issue started only after a recent iTunes update, here is what you should do:
- Close iTunes app
- If using a Mac, launch Finder and navigate to Go > Home in the Menu bar and then go to Music > iTunes. If you are a Windows user, open the following directory: UsersusernameMusiciTunes
- Now move the iTunes Library.itl file to your desktop
- Return to your iTunes folder and open the Previous iTunes Libraries folder
- Locate the library folder with the same date as the date you updated iTunes, and then drag and drop it into the main iTunes folder
- Just rename the file as 'iTunes Library', after you have moved it to the iTunes folder. For instance, iTunes library 2016-03-22 will become iTunes Library.
- After renaming the file, just relaunch iTunes and you should get back all the missing songs in there.
[Source: iDownloadBlog]