rca rd2825a 20gb

i have a rca rd2825a mp3 player.it was pluged into an a/c adapater by mistake, (12 volts) it uses a 5.5 volts adapter, it instantly quite working.is there anything i can do to fix it or to retrieve the music and info on the hard drive? also i have a buddy that has two of these same units that have also quit working i'm not sure why,but i wonder are these prone to defects? can anyone help? thanks for any positive feedback