When we delete a file on any device, the deleted file isn’t completely wiped.
What really happens is that the file system removes the path to access that file and marked the space that the file is using as being available for future use. But the file is still there, until they are overwritten with another new file.
So, when it failed to recover data, a probable reason is that the deleted file is already been overwritten.
If you delete files mistakenly, better to stop using your phone instantly and recover your data as soon as possible.