I can't find any iron , but I found gold and mined it with a cobblestone..

Iron is easiest to find a little above bedrock gold is easiest to find at bedrock like you said but you mined it with a cobble stone axe. In order to mine gold it must be iron which you can't find.f.y.i. You need iron to mine diamond. Gold can't mine diamond. Anyway iron like I said earlier iron is most commen found about 6 blocks above bedrock I hope you appreciate my answer and thanks for reading.

You need a metal pickaxe to mine diamond and gold

I tried listening to all directions and I got 50 blocks down and no iron! What should I do now. I am playing on my iPad so should I just choose a new world?

Your inventory must be full.