I copied my music into the music folder, but when i disconect from the computer, the player says that the music isn't there.

When you connect the MP3 player to your computer with the supplied USB cable then computer detects the player as an external storage device or a Removable disk, you can then view the folder on your MP3 player. Open the music folder and create a new folder on the player exactly the same way you create a folder on your computer's hard drive. To organise your music, make a folder name with the name of the music album and place the album's MP3 files in this folder, then copy the mp3 files from the computer into this folder.
You will then be able to select the music you want to play by the music album folder. To delete a file from your MP3 player, connect the supplied USB cable to your player and then plug it into the USB port of your computer.
The computer will detect your player then click on this device to view the files, you can then click on the music file to highlight the file and then press the Del key to delete the file off your MP3 player. MP3 players can only play music files in mp3 file format. You can download mp3 music files from the Internet to your computer and then copy them to your MP3 player using the USB cable. For your CD collection, you need to convert your CDs to mp3 music files onto your computer or download them from the Internet and then copy them to your MP3 player after you have connected the USB cable to the MP3 player and the computer.
You can do this using Windows Media player and Rip the CDs - Media Player will create a MP3 music file for each music track. Click on this link for instruction on converting music files to mp3 file format :- http://www.fixya.com/support/r5798418-creating_transferring_mp3_music_files

When you connect the MP3 player to yourcomputer with the supplied USB cable then computer detects the player as anexternal storage device or a Removable disk, you can then view the folder onyour MP3 player. Open the music folder and create a new folder on the playerexactly the same way you create a folder on your computer's hard drive. Toorganise your music, make a folder name with the name of the music album andplace the album's MP3 files in this folder, then copy the mp3 files from thecomputer into this folder.
MP3 players can only play music files in mp3 file format.You can download mp3 music files from the Internet toyour computer and then copy them to your MP3 player using the USB cable.For your CD collection, you need to convert your CDs tomp3 music files onto your computer or download them from the Internet and thencopy them to your MP3 player after you have connected the USB cable tothe MP3 player and the computer.
You can do this using Windows Media player and Rip the CDs - Media Player willcreate a MP3 music file for each music track.Click on this link for instruction on converting musicfiles to mp3 file format :- http://www.fixya.com/support/r5798418-creating_transferring_mp3_music_files

MP3 players can only play music files in mp3 file format.You can download mp3 music files from the Internet toyour computer and then copy them to your MP3 player.For your CD collection, you need to convert your CDs tomp3 music files onto your computer or download them from the Internet and thencopy them to your MP3 player after you have connected the USB cable tothe MP3 player and the computer.
You can do this using Windows Media player and Rip the CDs - Media Player willcreate a MP3 music file for each music track.Click on this link for instruction on converting musicfiles to mp3 file format :- http://www.fixya.com/support/r5798418-creating_transferring_mp3_music_files

MP3 players can only play music files in mp3 file format.You can download mp3 music files from the Internet toyour computer and then copy them to your MP3 player.For your CD collection, you need to convert your CDs tomp3 music files onto your computer or download them from the Internet and thencopy them to your MP3 player after you have connected the USB cable tothe MP3 player and the computer.
You can do this using Windows Media player and Rip the CDs - Media Player willcreate a MP3 music file for each music track.Click on this link for instruction on converting musicfiles to mp3 file format :- http://www.fixya.com/support/r5798418-creating_transferring_mp3_music_files

When you connect the MP3 player to yourcomputer with the supplied USB cable then computer detects the player as anexternal storage device or a Removable disk, you can then view the folder onyour MP3 player. Open the music folder and create a new folder on the playerexactly the same way you create a folder on your computer's hard drive. Toorganise your music, make a folder name with the name of the music album andplace the album's MP3 files in this folder, then copy the mp3 files from thecomputer into this folder.
You will then be able to select the music you want to play by the music albumfolder.To delete a filefrom your MP3 player, connect the supplied USB cable to your player and thenplug it into the USB port of your computer.
The computer will detect your player then click on this device to view thefiles, you can then click on the music file to highlight the file and thenpress the Del key to delete the file off your MP3 player. MP3 players can only play music files in mp3 file format.You can download mp3 music files from the Internet toyour computer and then copy them to your MP3 player.For your CD collection, you need to convert your CDs tomp3 music files onto your computer or download them from the Internet and thencopy them to your MP3 player after you have connected the USB cable tothe MP3 player and the computer.
You can do this using Windows Media player and Rip the CDs - Media Player willcreate a MP3 music file for each music track.Click on this link for instruction on converting musicfiles to mp3 file format :- http://www.fixya.com/support/r5798418-creating_transferring_mp3_music_files

MP3 players can only play music files in mp3 file format.You can download mp3 music files from the Internet toyour computer and then copy them to your MP3 player.For your CD collection, you need to convert your CDs tomp3 music files onto your computer or download them from the Internet and thencopy them to your MP3 player after you have connected the USB cable tothe MP3 player and the computer.
You can do this using Windows Media player and Rip the CDs - Media Player willcreate a MP3 music file for each music track.Click on this link for instruction on converting musicfiles to mp3 file format :- http://www.fixya.com/support/r5798418-creating_transferring_mp3_music_filesWhen you connect the MP3 player to yourcomputer with the supplied USB cable then computer detects the player as anexternal storage device or a Removable disk, you can then view the folder onyour MP3 player. Open the music folder and create a new folder on the playerexactly the same way you create a folder on your computer's hard drive. Toorganise your music, make a folder name with the name of the music album andplace the album's MP3 files in this folder, then copy the mp3 files from thecomputer into this folder.
You will then be able to select the music you want to play by the music albumfolder.To delete a file from your MP3 player, connect thesupplied USB cable to your player and then plug it into the USB port of yourcomputer.

When you connect the MP3 player to yourcomputer with the supplied USB cable then computer detects the player as anexternal storage device or a Removable disk, you can then view the folder onyour MP3 player. Open the music folder and create a new folder on the playerexactly the same way you create a folder on your computer's hard drive. Toorganise your music, make a folder name with the name of the music album andplace the album's MP3 files in this folder, then copy the mp3 files from thecomputer into this folder.
You will then be able to select the music you want to play by the music albumfolder.To delete a filefrom your MP3 player, connect the supplied USB cable to your player and thenplug it into the USB port of your computer.
The computer will detect your player then click on this device to view thefiles, you can then click on the music file to highlight the file and thenpress the Del key to delete the file off your MP3 player. MP3 players can only play music files in mp3 file format.You can download mp3 music files from the Internet toyour computer and then copy them to your MP3 player.For your CD collection, you need to convert your CDs tomp3 music files onto your computer or download them from the Internet and thencopy them to your MP3 player after you have connected the USB cable tothe MP3 player and the computer.
You can do this using Windows Media player and Rip the CDs - Media Player willcreate a MP3 music file for each music track.Click on this link for instruction on converting musicfiles to mp3 file format :- http://www.fixya.com/support/r5798418-creating_transferring_mp3_music_files

first connect your mp4 to your laptop with a usb cable. once it shows up on the laptop copy or cut and paste your music to the root folder of your mp4 or the music folder. after that is done disconect your mp4 from your laptop.

restart you mp4 and your music should now show up. enjoy your music

if it doesn't sync, don't worry just open the folder where the music files are stored on your computer, connect your Sony Walkman to your computer and highlight the music files you want to add to the Walkman and select (copy these files) a windows will open for you to select the place you want to copy to, select your mp3 player and click on copy to copy the selected music to your Walkman

NOTE: if you Sony Walkman has a specific folder for music files, you need to move the songs you copied from your hard drive's music folder to the music folder on your mp3 player for the player to recognize the songs in order to play.

Try updating your mp3 software. And reload your palylist and Art.