When I install a new SD card in my Canon PowerShot A540 it displays Memory Card Error Card Locked. I have moved the tab on the card and it displays the message regardless if the card setting. What

It's a lost cause. The A540 works with SD cards. While SDHC cards will fit into the slot, they are electronically incompatible and will not work in devices not designed for them. You need to stay with SD cards, 2GB and smaller.

There are several possible causes for "memory card locked", "memory card error", or "no memory card". The most common cause is having the tiny slide switch on the side of the card in the wrong position. The second most common is trying to use a 4GB or higher SDHC card with an older camera made before SDHC format came out. Please note that your particular model camera can only use up to 2GB standard SD cards. These are relatively inexpensive these days, and may be purchased on Amazon if your local store no longer carries them. There are also other common causes if the above didn't help, with troubleshooting steps for this problemlisted here.

There are several possible causes for "memory card locked", "memory card error", or "no memory card". The most common cause is having the tiny slide switch on the side of the card in the wrong position. The second most common is trying to use a 4GB or higher SDHC card with an older camera made before SDHC format came out (sorry, an A540 can only use 2GB or less standard SD cards. These are very inexpensive these days, and are available on Amazon if your local store no longer carries them). There are also other common causes if the above didn't help, with troubleshooting steps for this problem listed here.

There are several possible causes for "memory card locked", "memory card error", or "no memory card". The most common is trying to use a 4GB or higher SDHC card with an older camera made before SDHC format came out. Other causes include problems with the tiny slide switch on the side of the card, or the electrical contact switch internal to the camera. The problem may also arise from simple formatting problems if the card has never been formatted in the camera (note that this will also erase the card). Troubleshooting tips for this problem may be found at this link.
You also mention recovering photos saved on the card. If you actually did take pictures with this card (assuming it's a 2GB or less standard SD card, as 4GB SDHC was not designed for your camera), you may be able to recover the photos using recovery software. See this other link.

Have you noticed the slider on the side of the card? This acts as a lock and might have been accidentally moved to the locked position, in which case you could just move it back to unlock again. Hope this helps.

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. If the switch is already in the proper position, slide it fully the other way and then back again.

If that doesn't work, try another 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.

Hello(Read the whole solution)

OK, if the memory card itself is locked, you might sometimes get this error code. All you need to do is to take out the memory card and switch the lever on the left side to the unlock.



If the error is still displayed after you did the above, you might want to try the card in another camera.

If the card works in another camera . the problem is with your card reader in your camera.

If you open you sd slot and look inside with a sharp light , you should be able to see on the left side of the slot there is a little copper or spring steel lever switch. This switch work as follows:

1. When no card is inserted / no write protection , the switch is open and thus the protection is off.
2. When locked card is inserted , the tab is depressed and tells the camera that the card is lock.

Contrary to popular belief ,the little tab on the sd card is not an electronic switch and does not physically influence the card operation itself. If you put a locked card into a camera without a sd lock switch , you would still be able to use the card normally.

It is incredible difficult to fix this switch because of space limitations in the sd card. Look into the sd slot and if you can see the switch , use a needle to pull the little tab down toward the base of the camera by about 2mm or until it works being careful not to bend it.

If this does not resolve your problem , there might be a short in the switch circuit and the camera will need to be disassembled to resolve this error. This should cost no more than $50.

Please feel free to contact me if you need further information

Kind regards
Andrea

The A540 works with SD cards. Your 4GB card is actually an SDHC card. While it fits into the slot, it is electronically incompatible and will not work in this camera. You need to use SD cards, 2GB and smaller.

If it is an SDHC card your camera is too old to support it.  You need to get an older-style SD card.