While i copying songs my Samsung yp-u2 512 Mb player not showing any thing,what hapend to it

It like your samsung media player is invected by virus that make your file hidden
for problem like this i usually use smadav antivirus to scan it
you can download smadav antivirus at http://smadav.net
after download smadav antivirus connect your media player to computer, then double click smadav antivirus, check all drive at you computer include your media player, then click scan
wait until scan finish, after finish click fix all, and your file will back again

i hope this helpful
thank you for using fixya