|RAW isn't a real file system. Windows reports this when it reads corrupt data from the drive such that it cannot determine the file system. This could be caused by physical problems with the drive.|
The best option is to attempt data recovery.with a utility for the purpose. Attempting to repair the drive in place may make the problem worse.
This is just one of the reasons why you need a backup of important files. Data can be lost for a variety of reasons and you need to be prepared when (not if) something happens. Having a single copy of an important file is asking for trouble.