How to repair a disk volume:

Choose Volumes. Choose the disk and then Repair Volume.
Occasionally a file system on a disk may become corrupted or inconsistent, resulting in the disk no longer being accessible. You can use MainMenu to try to repair this problem.
Choose Volumes. Choose the disk and then Repair Volume.
Note that you can only repair volumes that you own. This typically includes USB sticks and other external drives, but may exclude other disk partitions.