loss of synch of key to car? Ford Galaxy 1.9 Tdi 02 reg?

my central locking was out of synch, had to lock unlock drivers door with key (wouldnt open by remote, but other doors did) i decided to re synch remote to car (as ford handbook instructions) but now cant get it to re synch and cant get into car without alarm going off, but can start car...how do i fix please help!!!!