I cannot seem to write any creative music. When I do write stuff it sounds like a direct rip-off of stuff I like. I try going for a progressive metal sound, but either it sounds like a direct cop from Octavarium or it's not metal enough.
Try to minimize your consumption of pop culture and music you normally would listen to. Like, go to your summer cabin, if you have one, and live without electricity for a week. Then while at it, try to write as much as you can and examine what you have written.
Learn different modes, such as Phrygian, and experiment with the notes within them.