My pny 2gb micro sd memory card is write-protected, i couldn't store or delete any files. what should i do? pls help me.

First check to see if it has a slide bar any where on the card itself to lock/unlock.

second download and install Sony EzRecover....

http://drivers.softpedia.com/get/Other-DRIVERS-TOOLS/Others/Sony-EzRecover.shtml

and use it to format the card (which will erase all data).
If that doesn't work select Control Panel --> Administrative Tools--> "Disk Management. Select the micro SD drive and click Delete. Right-click on empty drive and select New Partition.