External drive showing empty folder

Hello,
I have 1 Tb buffalo hard drive. whenever i open , it shows empty folder , however it shows 600GB of used space.
There are 3 folders. I am able to access 2 of them but the 3rd one is not accessible.

I have tried : attrib -h -r -s /s /d g:\*.*
but it returns back : access denied - E:\$RECYCLE.BIN
access denied - E:\System Volume Information\ tracking.log

I have run antivirus scan also but it could scan only 328 files which are from the 2 accessible folder.
When i use free software recovery tools , it shows all files and folders , however it asks for payment to be made before i can save those files.

Please suggest any method or any free tool to save all 600GB data without paying for the recovery tools.( which would be close to 100$ )