I've been using a Raspberry Pi 4 (headless) with camera module and Motion installed as a security camera. It worked pretty well for a while and then just stopped. I couldn't access it via ssh anymore so shut it down and tried to boot it up connected to a monitor and it would not boot up - I can't recall the exact error but it was to do with the SD card. So I put the micro SD into my micro SD adapter and plugged it into my laptop running Linux Mint and nothing happened. I tried a different micro SD in the adaptor and this one was recognised immediately but the first one produces, literally, no response. It doesn't show up when using the df utility from the terminal either. Unfortunately there was some video on there that I would like to retrieve. Nothing so important that I would pay thousands on data recovery services but I would be prepared to spend a few hours getting it back.
However, given the complete lack of recognition by my computer, how do I first establish if the data will ever be recoverable?
In response to one of the comments, the adapter is just the official Raspberry Pi microSD adapter so I can use it in a normal size SD card slot. When I normally do this, a window opens automatically showing the contents of the card. With the broken one, nothing happens. And nothing is listed when using the lsblk command either - it just returns the same output as when there is no card inserted:
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 113G 0 disk
├─sda1 8:1 0 512M 0 part /boot/efi
└─sda2 8:2 0 112.5G 0 part /
sudo umount /dev/sda1; sudo fsck -f -y /dev/sda; sudo umount /dev/sda2; sudo fsck -f -y /dev/sda2; sudo umount /dev/sda5; sudo fsck -f -y /dev/sda5; sudo umount /dev/sda6; fsck -f -y /dev/sda6ignore any errors. When that's completesudo poweroffswap the SDCards and see if your borken one now boots.sudo fsck -f -y) on a broken storage I try to recover. You risk to destroy it more. I would only work on a raw image of the storage (dd if=/dev/sda of=recover.img).lsblk.