WALKMAN sony

i have big problem i recieved a SONY WALKMAN NWWM MEM AAD2 Device (THIS IS HOW MY COMPUTER CALLS IT); the problem is that it doesn't want to play any music, i already tried a lot of formats but none work. I think tihs happened because I deleted a file named OMGAUDIO (it was about 20mb large on my sony walkman), please help me with this problem i don't know how to solve it. PLEASE IF YOU KOW HOW TO GET THAT "OMGAUDIO" FILE REPLY ME BACK. PLEASE!!!!!!