Check your microSD card on other system. If the same problem exist. Then it may be either corrupted or virus infected.
Formatting is the best options to get rid of such kind of error. It will instal a new file format on card and you will be able to use it. But formatting will erase all the files.
I know one of the very good Photo recovery
utility that recovers photos, audios and videos from corrupted and formatted memory cards.
You can download it from this link: http://www.stellarphotorecoverysoftware.com/download.php