Ps3 works with hdmi but not av

ok so few days ago i was playing fallout3 and it froze so i turned off my ps3 and when i turned it back on it had sound but no picture so i took i to a friends house and hooked it up using hdmi and it worked fine so i switched it back to av again and tried it but it still didnt have video only sound everyone says reset it by holding the power button till it beeps twice but that dont work can anyone shine some light on my problem?