A damaged File Allocation Table can cause the issue you are describing. This is not easy to solve, but can be.
Search for a program called Data Recovery Wizard that is made by EASUS. This program can see the files on your drive, even if the FAT table is damaged or gone.
- The program cost from $80 - $100.
- It takes days for the recovery to run, and then you still have to sort through hundreds of files to find the ones you want to keep.
- I have been successful in recovering all the lost files from 3 of 4 drives where I have used this program. The fourth drive was physically dead, and even this program could not see it, so there was no way to recover the data.
If you do not want to try this on your own, but need to get the data back, I would be willing to run the recovery for you, using my program, for a reasonable fee. If interested, we can talk about it.