There's a power feed to all the instruments and it sounds as if this has failed.  Could be a fuse - check the handbook for which one, but it may be that the plug on the back of the instrument panel has come off.  Take the instrument panel out to check - not too bad on most cars.  First figure out how the outer trim comes off then you'll see the bolts holding the panel in.  You may need to take the steering column shroud off.  It's fiddly but usually do-able, but go carefully otherwise it's easy to break things.   If it's a Grand Voyager, that only came out in 2008 didn't it - isn't it still under warranty?

Good Luck

Tim