I would make sure your graphics card is fully updated first of all.
Otherwise you can going to Program Files - osu! and find the osu!<Username>.cfg file. Then change the "Renderer" line to 'opengl' and save. After that try reopening osu!.
Is weird I've been playing osu for two mouth in this machine with no problems whatsoever, and the other day i opened osu and just a black screen with the music and interface sounds only.
Not sure if it would really help but have you tried changing the Renderer to "d3d" (DirectX) on the .cfg file mentioned above and seeing if it does the same thing?
Did you try making sure your graphics drivers are fully updated as I mentioned above? (Find out what model you have and go on the official website for it)
If your card is fully updated and you have tested on both Opengl and DirectX, you can try changing the frame sync line in the .cfg file to 0, 1, or 2 to see if it makes any difference. But the most likely problem is directly with your graphics card.