Currently asking for my friend, very recently my friend has recovered some old Xbox 360 data from an Xbox 360 HDD, the hdd appears empty on an Xbox 360 console so I suggested running a data recovery program on a PC by plugging in the hdd by sata to usb which recovered over 70gb of files, currently saved on his pc, now my friend is wondering how to put all of those files/folders back to the Xbox HDD. HDD is still currently formatted as an Xbox 360 HDD just no visibile data on the console.
Depending on what you have found Xbox 360 Content Manager can organise the files / folders how they should be on the hard drive. Party Buffalo Drive Explorer is a good way to copy data back to a 360 hard drive, although it does have issues in versions of Windows newer than 7. It's not free, however FATXplorer is probably the best hard drive management tool today in 2024. If the console is Jtag / RGH hacked you can just use FTP over the local network.