how can i fix a hydaulic clutch in a 1997 vectra b 2.0 sri?

hi as i was driving i lost all pressure in my clutch and theres no resistance,it was driving fine unil that hapened. i dont fink the clutch has gone as there was no burning smell. ive replaced the master cylinder and am about to change the slave cylinder. im just wonderin if any1 else knows off anythink else it could be can you please leave a reply tah