Do you get access denied / write protected error when you try to Format ?
If the format completes, just ensure that you had selected "full format" i.e. NOT the "quick format" or /q option
Quick format only writes the File Allocation Table. Full format will mark all bad sectors and capacity will be reduces accordingly but it will work properly.
Though you mention you have tried with diskpart, I am just mentioning the below in case you didn't do it:
1. Start > Run > cmd
2. type "diskpart" -> runs diskpart.exe from system folder
3. type "list volume" -> now you see all your connected drives, see which one is the drive
4. type "select volume #" -> # being the letter of your drive
5. type "attributes disk clear readonly" -> removing the protection
6. Then open your SD, you can now edit, delete, move files.
There can only be the following reasons for this write protect behavior:
1. Write protect tab is on lock position on the SD Card to Micro SD Card Adaptor. Are you using a sd card to usb adaptor ? If yes, can you try another adaptor or try formatting on the phone ?
2. File system is corrupt. Use a low level formatting tool like this , Low level tools will skip the file system drivers and write to the sectors directly. read here
3. Disk sectors are corrupt (ie Hardware on the card): In this case a low level format will just mark the bad sectors as such and disk capacity will be accordingly reduced but whatever is left will work fine.
4. The write protection thing is a very old tech using a small diode and light sensor and many issues are possible incl dirt which will start showing it as write protect. If you are using your laptop's inbuilt MMC reader then just try on another laptop or with a SD Card reader.
The following should not occur technically but sometimes they do occur due to some random bugs:
Did you put it into a Mac by any chance ? Sometimes it changes to GPT and gets really strange behaviour on windows & android. Though it only happened to me while trying to make bootable mac os disk on the sd card.
Do you have root on your phone ? If yes, Can you use a root explorer and try to select permissions and see if read only is selected ?
Did you by any chance put it in a blackberry with 'Encrypt SD Card" selected.
Can't think of anything else. I have only had this problem once with mac and once with google chromebook installer making 18 partitions with GPT on my microsd.
Google ChromeOS installer has an option to fix this so I am attaching that too.
It'll try to download 4 MB conf file you can let it do that or just remove internet so it fails. after that select options and select format usb drive and it will do its thing and then open windows format tool. Took me 2-3 tries to get my sdcard fixed.
chromeosimagecreatorV2.zip