|I'm assuming that you are NOT getting a message about the memory card being write protected or similar.|
You, or someone, have probablay damaged the data on the memory card because you, or they, unplugged it at the wrong time.
See response 2 regarding how you use Safely Remove Hardware:
By default, you can't delete a partition on a memory card (or a USB flash drivei) in Windows 2000 and up, but you can Format it.
However, if the file system's data is damaged - for the FAT, FAT32, or NTFS file system - on the memory card (or the USB flash drive), you can't successfully Format it, in Windows, or anywhere else .
If you have data that you DO NOT want to lose on the memory card that you know was there previously....
See response 2 regarding examples of which programs you could try to use to repair the data damage:
Or - if you DON"T CARE whether you lose the data that you may know was already on the memory card (or USB flash drive), use something other than Windows that can delete the existing FAT, FAT32, or NTFS file system on the partition (delete the partition), then make a new partition, then Format that partition. Some programs do both things in one step (Windows 2000 and up does both in one step if you are allowed to delete the partition).
- some cameras MAY delete the existing partition before they make a new one and then Format it when you select Format in the camera's settings.
- most programs on the web only Format the memory card (or USB flash drive) - they won't be able to Format it if the file system's data is damaged.
- you could try using the freeware Easeus Partition Master Home Edition to delete the existing partition on the memory card (or USB flash drive) then make a new partition and format it.
Memory cards (and USB flash drives)
- that have a 2 gb capacity or less usually use the FAT file system, but you could use the FAT32 file system.
- that have a greater than 2 gb capacity usually use the FAT32 file system
- if you have any that have a capacity larger than 32 gb, they would probably use the NTFS file system.