If you are not in the right mood, with your head in gear, and want to write, you will not be able to write. This is what is called Writer's Block. Almost every writer suffers from this debilitating affliction. If you are careful, you can avoid it. The mood you are in can play a part in how you write.
Cyberpunk requires a punkish mood.
There are all sorts of ways to change your mood. Check out some odd music. Heavy Metal sometimes works, but so does Techno and Industrial. If you have to, make up a tape and listen to it on the walkman. Dress up like your character.