Look under your seat and find the yellow wire that connects to your seat belt mechanism.
The most common problem is the wire has a connector under the seat this allows the owner or mechanic to remove the seat if works require the seat to be taken out....
If you have to car share with someone smaller or bigger than you the car seat has to be moved forward and back this can cause the connector to become disconnected or even lose. This may be the problem. It can be found in seconds and fixed as quickly. If it has become disconnected use some insulation tape to stop this happening again. Remember that this is connected to an explosive device in the front of the car, If you feel unsafe at any time you should contact a garage ASAP and get them to sort it out for you.... This is a very common problem and a great earner for your Garage...
Pat
December 2008