my mp4 looks like yours?
what can i do for format it?

You can test your player memory size with h2testw.exe which is free on the internet. It writes files to test the true memory size and reports.
Delete the files afterwards.

Gently push the reset (hole) with a straight paper clip to get back to normal. Off and back on should format it, or use regular XP/Vista format. It
does not affect the firmware.