Shelly is correct, most memory cards do have a slider switch to lock or unlock writing ability to the memory card. See attached image for the location of this slider on a SanDisk memory card
Most newer memory cards have a little tab on them like the old disks for computers, and by sliding over you can " lock " the card, inspect the card look for a tab, or little button, and see if you can unlock it.
Login using the form on the top of the page to post feedback (if you are a registered user). If you have not yet registered, click here to do so. It's FREE!.