I found a solution
I was caught out by this annoying iOS 11 and all my files was stuck inside “mydisk” app. After scrambling around with many useless advice. I finally came up with my own solution and got all my files back.
step 1: plug your device onto your PC and back up everything to itune.
Step 2: Download “iskysoft toolbox for iOS“ it is IOS Data recovery windows software and install in your PC. Cost about 70 USD (don’t pay for the whole suit of features only pay for the “data recovery“ feature. Save some money here)
Step 3: Launch the “ iskysoft“ toolbox for iOS software and connect your device to your PC, Click data recovery option And select the option “Recover from iTunes backup file”, this will scan the back up file itune created in step 1 above. Very quickply and quicker than scanning the whole device.
Step 4: when scanning is complete you need to export “App Data” file called ”mydiskIpad/Iphone” to your local PC hard drive, the button to do that is located at the bottom of the scan results window. Once exported open the folder on your pc and start renaming the files extensions ( .mov, .jpg etc) look out for large file sizes for movies and photos.
at this point you have Your files back and u can put them back into your device through file sharing or other means.