Restore from local backup: Open your file manager app to access your phone's storage.

 Locate the WhatsApp folder and go to Databases.

Copy the most recent backup file to your new device's Databases folder under local storage.

Install WhatsApp and verify your number.

Tap Restore to retrieve WhatsApp data from local storage.

Uninstall and reinstall   WhatsApp.

During the setup process, you will be prompted to restore your chat history from the backup.

If you have enabled iCloud backup, you can restore your chat history and retrieve any deleted messages.

 Dr. Fone - Data Recovery (iOS) can recover existing WhatsApp messages on your iPhone.

Use Aiseesoft Fonelab for Android: This app can recover lost WhatsApp data of any type, including media files and documents.