Salamz brothers! it is simple many people face this problem so, kindly check your mobiles' those pins which touch the memory card on back side of your mobile. There you will must see one or two pins would have gone punched due to sometime wrong inserting of memory card. just correct those pins and INSHA ALLAH your mobile will must detect your card. Hope it will solve your problem.
If u purchased orginal one it doesnt get problem, if its duplicate one it seems the same mgs again and again (sd card has dameged u cant use the same one, u wnat to replace the card) ... V3 support least 512mb card only not more than 512mb if use more 512mb capacity card the handset will get hanged.
Usually answered in minutes!