If you have ROOT ACCESS
This app scans and recovers deleted files from SD cards and internal
- Restore any file that has not been written over
- Works with documents, images, video, music, archives and binaries
- Save files directly to Dropbox, Google Drive and Sdcard
If you DONT HAVE ROOT ACCESS
The first thing to do is to connect the phone memory (internal or external) as a Mass Storage Device to your computer, ie, via USB.
Then download Recuva (you can use either the paid or free version), which is a program to recover files for windows.
When you run Recuva, the first thing to do is select the type of file you want to recover: Pictures, Videos, Music, Documents, etc. and set a specific folder to attempt recovery from. (In your case select image recovery from Sdcard/Whatsapp/Media/Whatsapp Images)
Other Free Data Recovery Softwares:
*Pc Inspecter File Recovery
*PicaJet Photo Recovery