how can i fix my clutch ?

my clutch has been fine throughout the time ive had the car but just the other day i have been pressind down on the clutch and changing gear but then the clutch sticks, it does not come back up, i have to give it a dunt with my foot then it will come back up. iam abit worried as i have been told that if i dont do something about it then it will affect my brakes too...