Can some one explain why the ps3 has stopped reading discs ?

May be...

it happened to me

Not quite sure. It could be just some hardware failure. If your warrenty is still active i would recommend going to this website to get it fixed:



http://www.us.playstation.com/Support



Be careful though, i've herd that PlayStation doesnt offer technical support to people who's PlayStation 3's have to must dust on them.

all discs or just one?

if it's more than one you need to either take it to a shop to see if it can be fixed or not and if they cant fix it you wasted like 600 dollars

now if it's just one disc thatn more than likely it's just the game

it happend to me too i stopped reading my games blu rays and dvds i was so mad i called sony and they told me i had to send it in and they sent me a box in three days and i sent it in and it cameback in one week