DO you know all pictures or videos you sent via whatsapp stores in a folder named 'sent'. You can see all sent items in your gallery. Check it out How:
Open ES Explorer in your mobile If you dont have then Download it from playstore.
Now goto left panel and enable 'Show Hidden FIles' Option
Now Go to internal -> whatsapp -> Media-> Whatsapp Images and you see here sent folder
Open Sent Folder and you will see a file name .nomedia
Just Delete this file and check your gallery. If still folder not available then just restart your mobile
and let it Refresh your internal storage.