How can I recover a deleted file on Android?

For deleted files on phone, as long as they are not overwrote, they can be recovered.
To find and get back deleted files or data from Android, I recommend PhoneRescue - Android data recovery, according to personal experience.
I've deleted some photos from my Galaxy s7 accidentally, with PhoneRescue I found them and retrieved them successfully. You can have a try with it, and it is pretty easy-to-use:

1. Run it on your computer (pc/mac) > Connect Android device to computer.
2. Select what kind of data you would like to recover > Click Scan button to look for deleted files, which would be like just dozens seconds, or a few minutes, depending on the data amount of your device.
3. Check the deleted files you would like to get back > Click To Computer button, and they will be transferred to your PC/Mac.

Recover files android designed for people to retrieve data from broken phone.This friendly software enables you to recover deleted contacts
It's a nice product that you shouldn't miss it.

How to Recover Deleted Contacts from Broken Android

Try GT Recovery for Windows! GT Recovery for Windows is a professional data recovery for Android phone or tablet. It can restore deleted photos,videos,audios,documents from Android SD card and internal memory. Whenever you lost important pictures or deleted photos by accident, you can use it to scan and recover the images on your Android devices.
Here are the steps to recover deleted data on Samsung Galaxy S4.
With this way you can recover deleted data on any brands of Android device such as Samsung, HTC, Huawei, Sony, Motorola, Lenovo, LG, Sharp, etc.
Google+:https://plus.google.com/communities/109657948177651590858
Facebook homepage:https://www.facebook.com/GT-Recovery-for-Windows-527139864132104/

Don't worry. You can get your data back by good app. Try Jihosoft Android Phone Recovery. This app has been helped a lot of users to recover data from Android phone. I used it when I accidentally deleted some important data from my Android phone. I was so happy to find all my data back. You can have a try. It should work.

It is no matter what kind of file you have lost. Because many data recovery softwares can recover all kinds of data. But first you shouldn't download any software to your Phone anymore or take pictures. It will overwrite your lost data. And you can use this software trail version to see if you can get the data back
http://www.imyfone.com/android-data-recovery

Not very understand what on earth the lost file is. However, you can still try a data recovery program on your computer. Connect your android to your PC and run the program. The tool would scan the lost files. Then you'll see what it has found. The last step is simply hit the "recover" button to start.
Recover Data from Mac Hard Drive and Storage Device

Vibosoft DR. Mobile for Android is professional and reliable android data recovery software, which can help you recover deleted, formatted, lost photos, video, music and other files from Android phone and Android Tablet safely and completely. It supports all version of Android OS. How to Recover Deleted Files from Android Phone