Why does my s120 keep saying memory card write protected?

When what is open? Always keep the battery / memory card door closed. If it is not closed correct, the camera won't work as expected. To protect the file system, when someone should pul out the memory card, while the camera is accessing the memory, it will or shut down completely, or at least protect the memory card against writing to it.
Before opening the battery / memory card cover, always make sure the camera is completely shut off. That means no light is allowed to burn or flicker. The memory card can also be write protected (SD cards) when the lock switch is down like in the picture on the 32GB card.
Before you can make any picture the switch on the card should be up like on the 64GB card on the picture.

Check the memory card theres a little switch on it make sure its in the correct position

If it's actually saying "write protect" then look at your memory card. SD and SDHC cards have a slide switch along one edge. The position farthest from the metal contacts locks the card, protecting it from writes. The position nearest the contacts unlocks the card.

Eject memory card and flip the white switch. If that doesn't fix problem some cameras can add accidental deletion protection which first needs to be disabled

Consider NOT connecting your camera to your computer.
The best way to download pictures from your camera to your computer involves removing the memory card from the camera and plugging it into a card reader (either built-in to the computer or connected via USB or FireWire). This is likely to be faster than connecting the camera to the computer, and won't run down your camera's batteries.
Once the card is plugged in, it will appear to your computer as a removable drive. You can use the operating system's drag&drop facility to copy pictures from the card to the computer's hard drive, the same way you copy any other files. Or you can use any photo cataloging program such as Picasa.

Look at your memory card. SD and SDHC cards have a slide switch along one edge. The position farthest from the metal contacts locks the card, protecting it from writes. The position nearest the contacts unlocks the card.

Look at your memory card. SD cards have a slide switch along one edge. The position farthest from the contacts locks the card, protecting it from writes. The position nearest the contacts unlocks the card.

Hi,

You have not mentioned the model number but this will help if your camera takes SD or SDHD cards.

Do you know that the SD card has a little switch on its side?
It is a small sliding thing on the other side from the cut out corner.

If this is in the lock position it will stop you saving your pictures to the card. This is to protect pictures that you want to keep.

To save pictures to the card the switch must be in the up position.

Hi there, My name is Rob and I can help you. Do this:

Make sure the camera is off and pull out the SD card. Look on the side of the card. You will see a little switch. One side says locked (or shows a little picture of a locked lock) the other side says unlocked (or shows a little picture of an unlocked lock). Make sure the switch is in the unlocked position and reinsert it properly into the camera.

This will fix your problem. Thanks for coming to FixYa. Let me know if I can be of anymore help. Don't forget to rate my answer a fixya!

Rob

Make sure the SD card lock is 'off' and then use thin, opaque sticky tape (ie non see-through; eg insulation tape) to cover the whole gap but keep clear of the metal contacts at the back.
The mechanical lock switch accidentally moves to the "locked" position during insertion due to the poor quality of the switch.