If the remaining battery power is low or insufficient, charge the battery. If your Walkman still does not operate after charging the battery, press the RESET button with a pen or a paper clip, etc. to reset your Walkman.

The data hierarchy levels of the content such as music transferred by drag-and-drop may not be correct. Place them in the appropriate folder and hierarchy.

Transferred files are not in a playable format. See “Supported formats” for details on the playable formats.

Content that are not recorded in playable formats are not recognized by your Walkman and will not be displayed in the lists.

When you transfer audio MP4 files by drag-and-drop, place them in the [MUSIC] folder of your Walkman.

Formatting your Walkman failed to complete, or you formatted the Walkman on the computer. Retry formatting the built-in flash memory of your Walkman.

The transferred data may be damaged. Delete the unplayable data from your Walkman and retransfer it, or delete the data from your computer and reimport it. When you import data, make sure that no other tasks are running on your computer until importing is completed. Otherwise, the data may be damaged.

If you change the file names or location of the content such as music that was transferred from your computer to your Walkman, the content may not be recognized by your Walkman and will not be displayed in the lists. Return it to the correct name and location.

If you have initialized (formatted) the built-in flash memory of your Walkman using Windows Explorer or the Mac Finder, initialize (format) it again on your Walkman.

The USB cable may be disconnected from your Walkman while transferring data. Transfer usable files back to your computer and initialize (format) the built-in flash memory on your Walkman.