Q: how to change the kind of file to a folder?

The first question is: what happened to make the folder appear as a plain file? I'd look at that first.

I'm not aware of any user actions that can have this kind of effect, so it might indicate some kind of disk corruption.

If that is the case, you can try booting to your Recovery Disk and running a disk repair. There are no guarantees here, but it might be able to restore the folder's settings.

See if you can start up in Safe Boot Mode. Safe boot mode startup runs a file system check.

Start up in safe mode

Then restart normally and see if the folder returns.

Hussain83 wrote:

 

I have tried to boot to Recovery Disk but with no luck.

Did you run Disk Utility - First Aid on the drive while in Recovery Mode or did you just boot into Recovery Mode?

Try running First Aid on the drive while you are in Normal Mode.

You could try re-indexing Spotlight. Not sure if it will help. Can't hurt.

Rebuild the Spotlight index on your Mac - Apple Support

I don't know if the Gopro uses its own software, but you may have better results seeking help from Gopro (maybe a Gopro forum) rather than through these forums.