Check the AC control unit mate... its the white box behind the AC controls (you have to remove a bit of dash to get to it... dead simple).
The VSS wire (Vehicle speed sense) passes through here, in the central of the 3 connector blocks.
I currently have this whole box unplugged from my car as i removed my head up display, and i drove without it yesterday and i have no speedo (or any other gauges)... could be that?
Having said that, there's not much to check, and i cant see the cables coming loose, so i dont know