If you bought it then reinstall it through iTunes.
If you downloaded it and didn't back-up, re-download it.
You can visit this tutorial: How to play iTunes iPod music video movie on Windows Media Player and vice versa
Honestly, I don't think that iTunes trades their music for the music you illegally downloaded.
Try reinstalling the driver for the CD drive
If they did not go into the Trash they may be in the Music folder within the iTunes Music folder within the iTunes folder in your Music section.
A utility such as DeTune (there are numerous other such utilities) can help transfer music from an iPod back to a Mac (there are numerous other such utilities for Windows users). (See links below)
Your hard drive has crashed and all of that great music you bought from the iTunes music store is on it. And as many times as you meant to back up your music, you just never got around to it. Don't worry, there still may be a way to get your music back.A friend brought me his crashed computer and we were able to get all of his favorite tunes back. His poor little Mac Mini was making a horrible knocking noise that almost certainly indicated a dying hard drive.Your Music is all on your iPod.If you have a iPod with your music stored on it, then you can just copy your data back from the MP3 player to your computer. Apple does not allow you do this natively, but there are several shareware utilities for Windows and Mac OS X that will do the trick.Music Rescue and iPod Access are both utilities that will allow you to copy your music back from your iPod back to your computer. Each program has both a Windows and Mac OS X version.If your music is not stored on your iPod, then you still have options to try. Sometimes a boot up failure is just a problem with the operating system and your hard drive is fine and so is the music on it. Some of the files important to Windows may be damaged and reinstalling the operating system will fix things up. In most cases, it is safer to try and copy your critical data like music off before attempting to reinstall the operating system. If you decide to try reinstalling the operating system, be careful not to erase the hard drive as you try to reinstall Windows or Mac OS X. If your hard drive is physically damaged, perhaps your music is not on the damaged part of the drive and you can still copy it off. The following data recovery techniques are customized for getting your iTunes music library back, they will work for getting any important data off of a computer that will not boot up as long as you know where the files are located and the hard drive is not completely dead.
if you have downloaded the itunes back. you have convert the itunes to the format ipod nano supported.
The music may be being added to an iTunes Music folder but iTunes is not finding that folder. In iTunes Preferences select the Advanced tab and click on the Change button to tell iTunes where the iTunes Music folder is located.
You cant feel It
All purchased music can be accessed and redownloaded both from your PC or Mac using iTunes, or by using the iTunes App on your iDevice.
he has previously gone to such measures as to change my windows password so as to access my itunes and music folders, he downloaded a software called Ilift that allows you to move music from the ipod to the computer, thus bypassing the password on my ipod and he has stolen my back up hard drive and downloaded direct from that. i knw you would say that its my brother but ive put alot of money into my itunes and hes getting it for free......... he has previously gone to such measures as to change my windows password so as to access my itunes and music folders, he downloaded a software called Ilift that allows you to move music from the ipod to the computer, thus bypassing the password on my ipod and he has stolen my back up hard drive and downloaded direct from that. i knw you would say that its my brother but ive put alot of money into my itunes and hes getting it for free.........
Because iTunes purchased music and video has DRM copyright protection, you have to remove the DRM at first, before you can convert/edit the audio or import it into Windows Movie Maker.In order to play it on non-apple mp3/mp4 players, you need to remove the DRM and convert the protected music to other audio /video format. The easiest way is to burn an audio CD in iTunes and rip it back as mp3 format.Or you can download free DRM Removal Software (you will need to Google it for download options).