You would have to look at whatsapps help info for restoring pictures through the app.
For restoring ones deleted on a device, first try restarting the device. They may actually not be deleted/gone. Sometimes things we do, or things we install, make the device not work correctly and it will temporarily hide some files. Should that not be the issue, or this not fix the issue, and you actually deleted things, then it is going to be hit and miss on if you can get them back.
While there is no guaranty that you can get them back. Deleted does mean deleted. There are a few apps/programs out there that 'may' be able to help you recover the data.
A few of the programs you could try would be... DiskDigger, MobiSaver, Android-Recovery and...