If You've purchased music from the iTunes store, go here: http://www.apple.com/support/itunes/store/lostmusic/

Go to the bottom of the page, Click Contact Us

Tell them your problem. they'll contact you and you may be able to re-download those missing files.

If there is music on your iPod that doesn't appear in your library:

Go To My Computer

Make sure hidden folders are shown by going to Tools > Folder Options > Hidden Files and Folders > Show Hidden Files and Folders > OK

Double click your iPod

Click on a folder named iPod_Control

Click on a folder named Music

Highlight and drag the music folders into your iTunes Library.

Note: This might not work if you synced your iPod with iTunes,

Step 1: take your i pod

Step 2: light a fire. i feal that a fire place is the best or in the midle of the woods in a campfire ring

Step 3: throw your ipod piece of crap into the fire

Step 4: smack your self or some form of inflickting pain on your self. something hard enough to get you to realize theres other stuff out there and to admit the wrongs youve done

step 5: go to nearest best buy.

step 6: buy a zune
WARNING THIS IS IMPORTANT!!!!!!!!!

Step 7: dont ever EVER!!!! buy a icrap again

step 8: sit back and be happy about the fact that your breaking from the hurd and not just geting the same dam thing everyone else has and having a creative touch and that you dont look like an ass/douch who puts a lower case ibefore everything even stuf that dosent have any thing to do with the ipod. yah its gona be harder to find stuff for the zune but hey thats the point to show manufatuors that there are other things out there other than the zune

Something you never hear anyone say:

"Glad i bought a zune instead of an ipod"

do you know why? because zunes are shit and i would rather have a fist in my ass that plays music than carry around a zune and look like a total wanna be man who follows his own path. ipods out sell EVERYTHING not because of the masses because they make a product that works sometimes there are problems but that comes in everything. Ipod obviously makes the best product so you should take your own advice go into the woods and throw yourself and the zune into the fire so we have one less douche nut in this world

In response to the person with terrible English skills who said that Zunes were better. You have not a clue what you're talking about. The Zune Software provided by Microsoft rarely works, and the music store (Zune Marketplace) is slow, and goes down often. What makes it any better for the average user? Plus, Microsoft's tech support is almost non-existent for the Zune, and yes, I have experienced all of this first hand.