I read once on anthropology.net that whatever music a person listens to when they're around age 18 will be roughly what they listen to for the rest of their life. I don't know how much truth there is to that, but if you make your own music, or even if you don't, it would be a good idea to break that stereotype right now. When I was 18, which I admit wasn't all that long ago, I was listening to a lot of electronic stuff, like Orbital, Aphex Twin, Radiohead and Squarepusher, along with the occasional game soundtrack and bluegrass CD. Honestly, I was very limited in my interests. As I got more and more serious about composing, I felt I had a responsibility to start learning more genres.
I am so glad I started branching out, because now some my favorite artists are Queen, Kansas, Camille-Saint Saens, Eumir Deodato, the Beatles (yeah I know, late start), Chuck Berry, Tito Puente, Run DMC, Bach and Chopin, to name a few. I knew next to nothing about them, say, 5 years ago. It's quite a variety, and one that I wouldn't have if I hadn't made a conscious effort to listen outside my musical comfort zone.
It's easy to avoid actively discovering new genres when you think you have no idea where to start. But I'm not letting you have that excuse. First, pick a genre that seems at least a little appealing to you but you don't know anything about it. Then do one of, or both of these things:
1. Ask a knowledgeable friend about the genre. You'll be surprised at how excited they'll be to assist you in your initiation. They'll point you to some of their favorites, and when you know a particular CD is their favorite, you're more apt to pay attention.
2. Use the ever popular Internet solution. I usually try looking up the name of the genre in Wikipedia. Wikipedia writers (Wikipedians?) usually make a list of prominent artists in that area of music on the main article. That's a perfect place to start. Plus you can learn about the history of the genre.
There's just too much fantastic music out there to simply ignore it. Anyone who says there isn't any new music out there obviously isn't creative enough to discover things on their own. Get new albums, put them on your mp3 player and randomize your playlist so the new stuff mixes with your old stuff and listen away. Listening to new music enriches your musical mind and can give you an infinite number of new ideas to work with. You will be a much more intelligent musician.