This error usually occurs due to virus attack, damaged file system, abrupt removal of card from system, etc. Due to this, you card becomes inaccessible & you may be on verge of losing data from it.
Watch this video completely to know about a software that can recover back your important data from the SD cards that throws not formatted error.
First you need to format the card using Quick Format option, in this way, you card becomes accessible again. Now, use the software to scan the card & restore the lost data from it.
Software supports recovery of almost all the media file types from these SD cards of various brands. To know more about the recovery, you can subscribe my channel & comment if you have any doubts regarding data recovery.