Help, black screen

[DreamWeaver21]

So I had my ps3 connected to my tv via regular AV cables, since I don't have an HDTV. The I decided to bring my ps3 to a friend's house who has an hdtv and a hdmi cable. SO I hooked it up there and it asked me to change the resolution settings so it would be compatible with my friend's tv, so I did.
But now that I connected it again to my tv, it isn't giving me that choice, insted nothing appears on my screen. I know it's not the AV cable's fault, nor my tv, since I used the same cable to hook up my ps2 and it worked. I don't know what to do here, help please.

[Shrygue]

Okay, what you should do is when turning on the PS3, hold down the power button for 5 seconds until it beeps. The PS3 will run a quick display detection test before loading the game menu. This should fix your output problem.