How to fix my sd card - Audio Players & Recorders

How to fix an HTC U12/U12 Plus that cannot read SD card, SD card not detected error [Troubleshooting Guide]

1. First solution: Reboot or soft reset your phone.
2. Second solution: Unmount microSD card then reseat it.
3. Third solution: Erase or format microSD card.
4. Fourth solution: Update phone software to the latest version.

https://thedroidguy.com/how-to-fix-an-htc-u12-u12-plus-that-cannot-read-sd-card-sd-card-not-detected-error-troubleshooting-guide-1088446

is the sd card lock ?
is the sd card formatted ?
can you put anything on the sd card file/folders etc ?
is the sd card recognized by the pc etc?

FIRST attempt to use the SD card in a different device /SD card reader like a phone, camera, printer or third party card reader. You need to find out whether there is a problem with the card or the reader is if the other device can see it access files or save files to the card and seems to be working correctly then it's probably a reader problem could possibly be drivers or the reader it's self. It could also need to be reformatted in order for your device to use the SD card. The other possibility is that the card has gone bad and then you will not be able to get it to work no matter what you do it does not take much to damage one of the SD cards.

When you need to delete the photos from the SD memory card, do not use your computer to do it. Use your camera to format the SD memory card.
To fix this problem, insert the SD memory card in your camera then go to the camera's Menu and format the SD memory card.

The most common thing that causes these problems is that an Incorrect format was done on the disk. Here are two different ways that you can fix these errors. I will give you the step by step way to fix them on each one.
First Way To Fix Your Issue:

1. Stick the SD Card back into the Card Reader on your Laptop or Desktop Device.
2. Open My Computer.
3. Right Click on the SD Card.
4. Select Format.
5. Format window pops up.
6. Under the Drop Down Menu of File System Select NTFS.
7. Then Click Format Wait till it finishes.
8. Then you should be done and the problem fixed

Second Way To Fix Your Issue:

1. Stick the SD Card Back into your Phone or Camera.
2. Select the System Settings on the device.
3. Select format SD Card on your device.
4. This should fix the issue.

If you are still having problems with this card then the SD Card is probably bad and needs to be replaced.

Lets check the SD card first.

Take out the SD card and put it in external card reader connected to computer.

Copy/transfer all the photos from the SD card to computer.

goto My Computer and right-click the 'Removable Disk' (the SD card drive) and click Properties.
click Tools and click Error checking - Check now button
select the option 'automatically fix file-system errors' and click Start button.
if any errors was found and fixed, you can also Format the SD card. And your SD card should not drop photos again.

Now put SD card back in the camera.

Now take 20 test photos and check if something is missing.
if not take 20 more test photos and check if something is missing.
if all is ok then you can delete all test photos and start taking normal photos.

Try asking someone else, have you tried updateing the firmware on the gps?