Check WhatsApp linked devices: WhatsApp Settings > Linked Devices
Log out of any device you do not recognize
Review recent chats for messages you did not send
Check for unknown archived, muted, or deleted chats
Look for changes to your profile photo, name, or about info
Check if your phone number is still registered on your device
Verify whether WhatsApp is asking to re-register your number
Check for unexpected verification codes by SMS or call
Review security notifications from WhatsApp
See if contacts report receiving strange messages from you
Check for unknown WhatsApp Web sessions
Look for unusual battery, data, or app activity on your phone
Scan your phone for malware using a trusted security app
Update WhatsApp to the latest version
Enable two-step verification in WhatsApp
Secure your SIM with a PIN from your carrier
Change your phone unlock code and email passwords
Reinstall WhatsApp if you suspect compromise
Contact WhatsApp Support if you cannot regain access