Vauxhall Vectra Central locking?

Hi, I have a 1996 Vauxhall Vectra. The only door that i can open is the drivers door. The other 3 doors and boot are all locked and will not open from the inside or outside. It is a 1996 P reg Vectra 2.0 CDX. It doesn't make any difference if I use the remote, or manually lock the drivers door. The others do nothing. Hope you can help. Thanks,
Martin