Reset the player before attempting to install new software to the player. Though the reset procedure varies from player to player, you can reset many devices by holding down the power button for an extended period of time, like 30 seconds, or by pressing the reset button on the device. If your MP4 player has a reset button, insert a straightened paper clip or pin into the reset hole as far as it will go to press the button and reset the player. Since resetting returns a player to factory settings, a reset restores the software on some players.
Download the firmware for your MP4 player if the player reset did not restore the software. The firmware for an MP4 player can generally be found on the manufacturer's website, as is the case for Creative Zen and Zune players. Firmware for other MP4 players, such as iPod, can be found on third-party websites.
Launch the synching software provided or created for your MP4 player on your computer. Creative Zen and Zune players come with software installation discs, which contain desktop software that allows your computer to integrate your MP4 player. iPod uses iTunes software, which can be downloaded for free from the Apple website.
Go to the "Downloads" folder on your computer if you have a Windows system. On a Mac computer, go to the desktop to find the MP4 player software you downloaded.
Double-click the file for the MP4 player software and follow the on-screen instructions provided. The software installs on to your MP4 player through the desktop software.