ldv has cut out help!!!!!!!!?

hi while driving my diesel LDV with a Ford Engine today i changed gear and the engine cut out. it is now dead on the key and wont turn over, the oil light and spanner light stay on, also the immoboliser light flashes as normal untill i put the key in and turn it and the immoboliser light goes out and will not come back on untill i have turned the key back to off. please can anyone help?