Download any Linux distribution and open a virtual terminal or terminal. Then do next things on bash:
1. Log in as root with su program by typing "su" and give root password (check distributor help page what is root in Live mode if using such).
2. Use dmesg and tail programs to get device information by typing
"dmesg | tail"
3. Physically connect your MicroSD card to reader
4. Re-use dmesg and tail programs to get device information of connected MicroSD by typing
"dmesg | tail"
5. Read what device was connected (Example /dev/sdb (! Not /dev/sdb1 or anything else number, just /dev/sdX)) from the output what dmesg program gave you when connected the MicroSD card
6. Overwrite whole card with full of zeroes with dd program and zero generator by typing
"dd if=/dev/zero of=/dev/sdX"
!!! IT WILL DESTROY ALL DATA ON CARD AND PARTITION TABLE !!!
and just wait that dd program write the whole card full of zeroes. of= means "Output File" and if= means "Input File". Be very careful that you have correct MicroSD card targeted (of=).
7. After you have cleared the whole card, eject it from card reader and re-insert it.
8. Re-use dmesg and tail programs to confirm the same device file is used
9. use fdisk program to create a new partitions and partition table to the card by typing
and press m for help. You need to create a new primary partition (n) and then write it to disk and quit (w). You can print already existing partitions with p as Print.
10. Eject the card and re-insert it
11. Use again dmesg and tail program to confirm new device files and partitions (Example, now there should be /dev/sdb, /dev/sdb1 if created one partition)
12. Generate a filesystem on created partitions and write them to partition table with filesystem tools (fat32 filesystem usually is wanted) by using mkfs.vfat program.
Type "mkfs.vfat /dev/sdX1"
13. Eject and re-insert the card
It should now be working again, with FAT32 partition on it.
P.S You can skip 7-13 parts if you want to do partitions on Windows, I always do it on Unix because Windows might get things still wrong but after the partition table is re-created on Unix, it works on Windows as well.
I have fixed dozens of "broken" cards and sticks by this way.
If you can not get your card listed with dmesg program then that card is physically broken, NAND chip is gone gaga or your card reader is broken as computer does not even recognize the card at all.