Faders not working, play buttons not working...

I have a DDJ-SB and Traktor 3 - worked fine the last time I Used it - set it all up again but neither fader seemed to adjust the track volumes on either deck although moving the cross fader to the left faded out both decks.

I've been reading the forums and downloaded some .tsi files and made sure the SB firmware is up to date.

Now along with the original problem the play buttons on the DDJ-SB do not start or stop tracks - the cue works but can't start the tracks playing on either deck.

It's doing my head in!

Should I delete any preferences and reset Traktor to factory defaults and if so how do I do this?

Hopefully someone knows a simple fix...

Thanks