If you lose your phone or it becomes stolen, it’s important to lock your SIM card as soon as possible at your mobile provider. After that, you can follow the other steps below.
1. lock your simcard
Whether you’re using WhatsApp or not: if you lose your phone, contact your mobile provider to lock your SIM card. If you don’t lock your SIM the finder or thief can use your mobile services at your costs.
Once you’ve locked your SIM card, it will not be possible to verify your WhatsApp account on the lost phone. (In order to verify WhatsApp, your phone needs to be able to receive SMS or phone calls and that’s not possible with a locked SIM card).
You have two options to deactivate your WhatsApp account without access to your stolen/lost phone:
New phone, SAME phone number (new SIM)
The fastest way to deactivate your WhatsApp account on your lost or stolen phone, is to activate your account on a new phone, using a new SIM card with your original phone number. As soon as you’ve activated your WhatsApp account on your new phone, the old one will be deactivated. WhatsApp can only be activated with one phone number on one device at a time.
Make sure you’ve locked your SIM card on your old phone first, otherwise the finder or thief is able to reactivate your account again.
New phone and NEW phone number
If you can’t use your old phone number on a new SIM card or you decide to change your phone number for another reason, you need to contact WhatsApp in order to deactivate your lost account.
Send an email to firstname.lastname@example.org with the phrase “Lost/Stolen: Please deactivate my account” in the email body and include your full phone number (international format with a plus sign)
If you don’t contact WhatsApp to deactivate your account, your WhatsApp account can still be used on your old phone with Wi-Fi.
When your account is deactivated it’s not entirely deleted. Your profile info is still visible for your contacts and your contacts can still send you messages (but will remain pending with one checkmark up to 30 days). If you reactivate your account before it’s deleted, you’ll receive pending messages on your new phone and you are still participant in your group chats. After 30 days without reactivation of your account, your WhatsApp account will be deleted and your pending messages are removed.