I can't get my music to sync to my iPhone

Oh, yeah, I have a zillion playlists! The funny thing is -- and I just noticed this last night -- that all of my songs seem to be missing from my playlists! So, that appears to be part of the problem.

mine is doing the same and it's really annoying me, also none of my apps are working except the original ones on the iphone.
i tried removing all music resyncing etc but nothing works

i have the same problem. i just got my iphone and i had my itunes on an external drive to install another program but when i tried to sync it it did nothing. it wouldnt even show up on my computer except to put my pictures into iphoto

I think I knoww what your problem is.
When your in Itunes and have your Iphone connected.

Go to the Iphone on the side of the Itunes and there will be catagorys click on music and click on the box that says "Sync music" I dont know why but when you update an Iphone it'll not have the box checked to Sync.

This worked for me - once I got iTues to recognize my iPhone, Rai's suggestion worked - I was getting no music. mark

I had the same problem, but the "Sync Music" box was checked, so that wasn't my issue. I discovered, however, that the individual songs in my Playlists had been "unchecked" (there is a little checkbox to the left of each song). I checked all of these boxes and then re-synced. Voila! Finally ... success!

My 3GS suddenly stopped syncing my entire playlist after I changed it up a bit, and I spent a couple of hours fooling with it. The checkbox solution worked like a charm. All synced up now!

I had the same problem, and none of the solutions worked for me. After updating to 3.1.2, I installed Installous, and checked the "iTunes sync" option. That was stopping iTunes from removing the unauthorized software, but also stopping it from syncing.
So go to Installous on your iPhone, uncheck "iTunes sync" under Settings and sync your iPhone freely. Be aware that this action will remove any illegal software installed via Installous.

I hope this helps :)

I plug my iPhone to the computer and the iPhone icon not even is shown on the iTunes and I do not why

I think a lot of you are having a simple problem--it isn't automatically putting music on your iphone. So here's how i would explain the steps to my mom:

In itunes, click on "device" (iphone symbol).
Then on the screen where it shows a summary of your space used and available, select the "music" tab.
Then you have to check the box to sync it with your current itunes library. I've been trying to keep my bought music on my iphone and just add my itunes library to it, but it won't do that.
So if you have purchased music you don't want to lose, you have to go back to that device menu and "transfer" purchased music (right click on the music symbol under device) to itunes. You'll see it's progress in the status bar at the top.
Then go back to the Sync Music? tab. It might tell you it is synced with another itunes library, erase it? Click yes, (because you've just saved that music to your computer)-- you can now check boxes to select what playlists, artists, purchased music, etc. to put on and leave off.
It'll say "backing up so-and-so's iphone" for a long while if you have my issue of a lot of apps. Just leave it plugged in and come back to it in a while.

I hope this helps one or two of you with your problem!