Open WhatsApp and check whether the chat is archived
Tap the Archived section and unarchive the chat if needed
Restore the chat from a recent backup
On Android, uninstall and reinstall WhatsApp, then verify your number and tap Restore when prompted
On iPhone, reinstall WhatsApp, verify your number, and tap Restore Chat History when prompted
Make sure the backup exists in Google Drive on Android or iCloud on iPhone
Confirm you are using the same phone number and the same Google or Apple account used for the backup
Check that your device has enough storage space to complete the restore
Update WhatsApp to the latest version before restoring
If the chat was deleted and no backup exists, it cannot be recovered through WhatsApp
Ask the other person to resend the messages if needed