4 GB ms card problem

Hello,
I'v a 4GB TRANSCEND Micro SD phone memory card. Recently i set password for my card which i've forgotten. I remove the password using nokia E series. But now the problem is that, i cannot add any data onto it. Neither can i format it. I tried both in cell n in pc bt to no avail. The pc says it cannot complete the format. Please help.
THANKING YOU IN ADVANCE.