Hi Gwendoline,
I'm Ahmed and I am here & happy to help.
Sorry for having this issue,
Kindly try the following troubleshooting steps:
1- Go to WhatsApp > Settings > Chats > Media visibility (toggle on)
2- Clear WhatsApp Cache:
a- Go to Settings > Apps > Manage Apps.
b- find and tap WhatsApp. Go to storage and hit "Clear data."
3- Restart Your Phone and check
I hope this helps! Let me know if you have any further questions or concerns.
Best regards,