Captioning stopped working

Question

the tv is 37" lcd and about 2 years old. today the captioning wouldn't turn on. we usually turn it off during the day and turn it on at night when our baby sleeps. we tried to turn it back on and it wouldn't come on. the only option that ever works if the one labeled C1. and now it won't work at all. please let me know if there is something that can be done.