I HAVE SYNCHED THE MUSIC BUT ONLY THE SONGS THAT WERE ALREADEY ON WILL PLAY

Just to be clear,most players require no special drivers. MSC mode will work out of the box with just about any MP3 player and any OS (W*ndows Linux). MTP mode will work as long as you have WMP 10 or 11 installed. Firstly, I will try to explain MSC mode and MTP mode and what they mean. MSC stands for Mass Storage Class. When your player is in this mode, the computer will see it the same way it would see a Thumb drive or flash drive, as a removable disk. It will assign the first available drive letter to your device, as well as one for the memory card (if it uses one and it is installed). This is probably the more popular of the 2 modes, and is a more "open source" type of standard. Most computers detect the player in this mode without a problem very well and right away.
MTP stands for Media Transfer Protocol. It is a Microsoft standard and is Microsoft's solution to connecting MP3 players and cameras to a w*ndow based Computer. MTP mode must be used in order to transfer ANY Digital Rights Management (DRM) protected content. MP3's downloaded form services like Rhapsody and Napster will only function in this MTP mode.
Most good MP3 players will have both of these modes at the users options.
Although not all do, so it is a good idea to check yours for these settings if you are having connection problems
NOTE: Any songs added to your player in MSC mode will not be available in MTP mode and vise-a-versa. In other words You can't see the files added in the other mode and you can not play them. You know you have some files on your player and can not find them now, you may have to change modes so they are available. Some players in the SanDisk line up use Instead, an "Auto Detect" function that is suppose to Automaticly use MTP mode. If MTP mode does not work for any reason, it should default to MSC mode.
To use MSC or MTP modes go to your players settings.
These settings will vary based on player model and you might have to refer to your users Manual. Check their web site for a download in PDF form. Turn the player on, if it is not already Navigate to the main menu of your player; this is the same menu that gives us options such as Play, Record, Info, etc... Navigate to "Settings" on the main menu of the player. After navigating to "Settings", you should see an option that states "USB" or "USB MODE" From here we can select MSC or MTP modes (could vary based on player model) Highlight the desired mode and select it, at this point it will roll back to the 'Settings' menu Connect the player to your computer and verify it is connecting in the desired mode. It should be noted, when a device is in MSC mode, it will appear as a "Removable disk". When connected in MTP mode, it will show up as an "Audio Device".
Now most players now days can and will use`MS W*ndows Media Player. You can also try to reinstall W*ndows Media Player 10 or 11 Next W*ndows has a update to fix if all else fails try this link. http://www.microsoft.com/downloads/details.aspx?FamilyId=A2E73160-E862-4F19-BB26-C0CAFE798955&displaylang=en