Have a look at the right most fuse in the fuse box under the Glove box, usualy red 15amp fuse, if that has gone nothing to do with the head unit or speakers will play ball till that works again.
failing that you may have wired the connectors up wrong, I have a feeling i have done the same. My head unit works and plays and everything, but when I switch the ignition off it still carrys on.
I couldn't of wired it wrong, because I was using the Head Unit for a year before I added more speakers.
Does the car start still? (What I mean is, you haven't got a flat battery have you?)
Yeah car starts fine I drove today, I'm a bit confused to why it's not working tho, because Yesterday It did work until it came to securing into its place. I'll check the fuse when I get home.
Still I'm confused to how it happened, doesn't seem to be a logical reason for it to work and then not to work!