EOS M100 Memory card error and camera don't show photo

[KenV]

So I taken about 300 photos on my eos m100 camera. When I get the memory card out and plug it in my by using a adapter to download photo, i didnt know how to download it so then i put my memory card back into my camera and taken some more photos. I found a way to download the photo using the app but then when i try to do it i found out that all of my photo are gone, only the one i had taken after i put my sd card back were still there. Then I check the camera photo gallery, I found that the other photos were actually gone. But when I plug the card back into my phone, the 300 photos were still there, in the car. My memory card is a Lexar265gb the adapter is also lexar. My camera is a eos m100. How do i fix this? My camera doesn't recognise the other photos.

[ebiggs1]

If you put the SD in a computer are the photos there? Are you using a micro-SD? Although others will tell you not to do that and I also recommend not using one but, they do work and may or may not be the problem. See if they are there on your computer first. Do not use that SD or format it beyond checking for photos. There is recovery software that can under certain circumstance bring them back.

[KenV]

When I plug it into the computer, the photos are still there

[KenV]

Yeah, Im using a microsd card

[Tronhard]

Hi Ken and welcome to the forum:
Unfortunately, you should never use a micro-SD card via an adapter with a camera that does not specifically indicate it is compatible.  The Micro-SD cards uses a different internal technology within the card compared to a full-size SD card, and the adapter also introduces a dry joint between the card and adapter  that creates very unreliable results, especially when trying to use high-speed download.  You will find this an on-going issue unless you switch to a full-size card.   

The following advice from How to Choose the Right SD Card Sizes for Your Tech Needs (lexar.com) clearly states that for cameras the full-size card is the correct format.  Action cameras are things like Go-Pros or some tough cameras. 

Note that in the manual for the M100, on P24, Canon recommends using SD cards 'conforming to SD standards" with no mention of Micro-SD card format. (User Manual (c-wss.com))