I have a year old Sony mp3 player, and now it is malfunctioning. what do I do to fix it?

Like I said, I've had it a little over a year. And I uploaded a few songs last night, then when I turned it on and went to the music section of my menu, I couldn't get to the album I just downloaded. Actually, I couldn't get to any album/artist/genre. I listen to my mp3 player every night, and I can't leave the house without it. But, it annoys me when I can't access my stuff the way I want to. PLEASE HELP ME!!!