why my Memory card are always not work

6 Memory Card Problems and How to Solve Them

Listed below are six common problems that can occur with memory cards. Straightforward solutions are presented for each issue, so that users will not face the problem of shooting photos with no way to store them for sharing later.
1. Memory Card Is Write Protected or Locked

SD memory cards have a lock on them that prevents memory from being stored on the card while the lock is on the "on" position. If the memory card is in the locked position and the user tries to record photos or videos, a message will appear, signifying that the memory card is write-protected or locked.

The solution for this problem is simple. SD cards and their variants (SDHC and SDXC cards) have a lock switch on the left side. If the lock is in the bottom position, slide it up to unlock the card. If that still does not unlock the card, toggle the switch back and forth three times and put it back into the locked position for thirty seconds. After half a minute, slide the switch into unlocked position and try to shoot some photos again. If the camera still gives a message indicating the card is locked or write-protected, format the card (see section on formatting below).
2. Card Cannot Be Used Error Message

Sometimes the camera will display a message that the memory card cannot be used. In this case, it is not clear what the problem is, only that the camera is not properly reading the card. When a user receives this message, the first step is to turn the camera off and back on, making sure not to do so while the camera's busy light is on. The user should then be able to view photos and videos by pressing the camera's playback button. If this still does not solve the problem, the user should try to back up the card's data on the computer and format the memory card.
3. Missing or Unreadable Files

A memory card may be working just fine, recording all of the photos and videos that the camera is capturing, but some of those photos and videos may appear to be missing or unreadable. In this case, an external solution is required. The first step is to acquire data recovery software and run the memory card through it. Good data recovery software should be able to restore the seemingly lost photos and videos.

If software still does not work, the memory card can be taken to a computer or camera repair center, or sent to a data recovery center. These service providers have top-notch software and machinery that may be able to help where data recovery software could not.

Whether either of these methods is successful in recovering photos and videos or not, the memory card should always be formatted after recovery is attempted.
4. Memory Card Runs Slowly

At times, it might seem like a memory card is transferring data much more slowly than usual. In cases such as this, it may not actually be a problem with the card. As previously mentioned, every memory card has a speed rating that indicates how quickly photos and videos can be transferred from the card to another storage device. If the card has a low speed rating, transfer times will be longer.

It is also possible that the memory card is performing sub-optimally. In this case, formatting the card may solve the problem.
5. Damaged or Corrupted Card

Memory cards are sensitive devices that are prone to damage. Many different things, such as immersion in water and being subjected to extreme heat or cold, can damage or corrupt a memory card. In this case, the memory card is generally unusable. The best that the owner of a damaged or corrupted memory card can hope for is to recover the data on the card. It is therefore recommended, in this case, to employ data recovery software or the services of a data recovery specialist.
6. Computer Will Not Read Card

Sometimes a computer will not read a memory card, even though the memory card works just fine with the camera. This is problematic because it makes transferring photos and videos to a practical storage device inconvenient. The issue here is likely with the computer, rather than with the memory card, so computer-based solutions will likely solve the problem.

The first thing that a user can do is try a different USB port. Failing that, the user can try downloading drivers for their computer's operating system. Some older computers with older operating systems are not capable of reading memory cards larger than 2GB, but updating the operating system's firmware generally solves the issue by making the operating system compliant with larger memory cards.