Mk III or Mk IV? Could be either in a 99. If the motor is making some noise (trying to work but no action), it could be the linkage. Just went through this on my Dodge. A few bushings and I was back in business.
Both need the wiper arms off and then the rain tray removed to check the linkage. MK III is a little easier to get at I think. Work from a corner on the tray and don't pry against the glass. After the tray is off try and reach in to check the linkage. If it is loose enough it could bind up and you should be able to feel that.
Some blue sky here in the burbs (G. E. bridge) so maybe you can make it home without needing the wipers. Better driving in the daylight without wipers in any event.
The Vortex is full of how to's. Good luck.