Dragonball z videl and gohan question gohan dead by buu?

for dbz fans you know when everyone thinks gohans dead by buu and kai brings him to get the z sword and train? goku tells videl and every1 hes dead than buu comes and turns videl bulma and chi chi and them to candy, even no gohan isnt dead, and they think they are, which episode do they find out that he is alive? does anyone know if they ever find out hes alive? like in the underworld do they ask someone or soemthin