I'll try be of some help to you and just throw out a few ideas that'll maybe get you thinking!
Ok, so think about when it is that you listen to music,or read a book, I'd imagine for the most part it is when you are relaxing, evening time maybe? and sitting down, maybe lying down. So, an item that stores your CD's/books that is easily accesable whilst sitting/lying would be preferable. It'd be a divil to have to get up everytime you wanted to change a CD!
Books and CD's say a LOT about people, thats a fact! And you'll find that those whom are proud of there CD/book collection and want to make a statement with them will have them out on show, now, some might have them all neatly arranged, others might have them in a bit of a heap, but even these methods of displaying them say something about the person. So definately the CD's and books should be on show, they should be seen and not hidden away. Its like the cloths we wear, the car we drive or the food we eat, our taste in media says a lot about the person, so I'd try keep this in mind when designing the piece.
With regard to 'investigation/research' what you have to do there is have a look about and see what other methods of storing/displaying books/cd's are availible on the market. Look up Argos books and other catalouge and see what is on offer, materials used, prices etc. Basically look at everything from shelves to cabinets and show your teacher/marker that you have gone out there and had a look, understood what was avilible and gained some knowledge as to what was required from your item.
Look at what woods might work best, what colors would suite the piece (if you are going for something relaxing for those whom enjoy evening time reading, perhaps some pastel tones) maybe even a light fitting or some form of illumination? Maybe a light to aid reading, or soft under lighting/LED's to lift the piece off the ground or create a relaxing atmosphere. Look at shapes, curves, styles, as its for storing cd's too(?) look up musical notes and rythem charts, see if you can get any inspiration from them
If you do all of them above I guarentee you teacher will be well impressed and you'll be well on the way to making a good project!!
As I mentioned earlier, look at ways that you listen to your music/read, when you do it and for how long, determine if there is something you would like to make this time more comfortable or enjoyable. Perhaps, as mentioned, easier access to your media.
At this point you shouldnt be thinking about what the product will look like, forget that! Really, do, you might not think it, and its a mistake that many (including myself make) but you have to do your 'investigation/research' first and do that with an open mind. From that you can start getting a better picture of what you will need, it'll give you the bones of the idea around which you can wrap a shape/style. Dont be afraid to go a little 'out there' and step off the beaten path, you'll get just as much, if not more points for something a little wacky that works, than something simple and safe that also works.
If ye need any more help just shout!!