Folder becomes invalid after trying to create a nameless folder inside it by mistake! My first post on stackexchange.
I was trying to change the name of a folder inside another folder in my extsdcard. I cut the name. But unfortunately pressed the rename button before inserting  a new name for the folder. Now the parent folder becomes empty, only a file named "invalid " (0.0 byte) is in it.  Other files &amp; folders are not there. 
Is it possible to recover the files?
You should try to put your SD card into a linux computer.

Then make as soon as possible a dump of your SD card using dd. In this way you'll get an image which you can use for recovery trials and avoid to brick your original device.

Then you can use this image (or a copy if you modify it) for your trials.


First try just to mount it and see, if it possible to access it and the relevant files.
If this does not help, you should use fsck to hopefully recover your lost files, results are typically stored in the directory lost+found.
If this all does not help, you should use a tool like testdisk to recover all kind of lost and deleted files. (However, this method will be most likely have a chance to be successfull, if there have not been to much write operations on the SD card, as every write operation might overwrite any lost files).