This wikiHow teaches you how to lock a lost or stolen smartphone. Phone locking makes the device inaccessible or reset (even via hard reset). This means that the phone cannot be used at all until you unlock it. You can block a lost or stolen iPhone, Android device, or Samsung Galaxy phone using the “Find” website of the device manufacturer/manufacturer. However, a device search service (eg Find My iPhone) must be available and enabled on the phone in question.
Step
Part 1 of 4: Using the Find My iPhone Feature on iPhone

Step 1. Open the iCloud website
Visit https://www.icloud.com/ via a web browser.
This method can only be followed if the Find My iPhone feature is already enabled on the phone

Step 2. Sign in to your iCloud account
Type in the Apple ID email address and password, then click the → button.
If you're already signed in to your iCloud account, skip this step

Step 3. Click Find iPhone
This radar icon is on the iCloud page dashboard.

Step 4. Select iPhone
Click the tab All Devices ” at the top of the page, then click the iPhone's name from the drop-down menu that appears.
If your iPhone is the only Apple device registered to your Apple ID account, you don't need to follow these steps

Step 5. Wait for the device location to be found
Once your iPhone is displayed, you should see a pop-up window in the top-right corner of the page.

Step 6. Click Lost Mode
It's at the bottom of the window. After that, a new page will open.

Step 7. Enter the phone number
Type in a recovery or backup phone number where you can be reached. This number will be displayed on the device lock page.
This step is optional, but recommended if you think your phone was accidentally left behind, and not stolen

Step 8. Click Next
It's in the upper-right corner of the window.

Step 9. Enter the message
Type in the message you want to appear on the phone screen.

Step 10. Click Done
It's in the upper-right corner of the window. iPhone will enter lost mode or “Lost Mode”. This means that the device cannot be opened or used until you remove it from the mode.
You can turn off the mode by clicking on the option “ Lost Mode " and choose " Stop Lost Mode ” at the bottom of the drop-down menu.

Step 11. Clear data on the phone if necessary
In the worst case scenario, it would be better if you erased all your phone data rather than letting it fall into the hands of an unknown thief. To clear data:
- Click " Erase iPhone ”.
- Click " Erase ' when prompted.
- Enter your Apple ID password and other requested information.
- Click the button again Erase ”.
Part 2 of 4: Using Find My Device Feature on Android Device

Step 1. Open the Find My Device website
Visit https://www.google.com/android/find via a web browser.

Step 2. Go to the website
Type in the email address and password of the Android account you want to lock.

Step 3. Select the phone
On the left side of the page, click the icon of the phone you want to lock.

Step 4. Click LOCK
This tab is on the left side of the page. After that, the menu under the button " LOCK " will be opened.

Step 5. Enter the password
If your Android device does not have a passcode, you will need to type a temporary password in the " New password " and " Confirm password " fields.

Step 6. Enter the message
Type the message you want to appear on the lock page in the " Recovery message " field. This step is optional, but recommended if you think your phone was accidentally left behind, and not stolen.

Step 7. Add recovery phone number
Type a phone number that can be used to contact you in the "Phone number" field. This phone number will be displayed on the device lock page.
As is the case for recovery messages, this step is optional

Step 8. Click LOCK
Step 9. Wipe device data if necessary
In the worst case, it would be better if you delete the data on the device rather than letting it fall into the hands of an unknown thief. To delete data on the phone, select the device, click the tab “ ERASE ”, and follow the instructions that appear on the screen.
Part 3 of 4: Using the Find My Mobile Feature for Samsung Devices

Step 1. Open the Find My Mobile website
Visit https://findmymobile.samsung.com/ via a browser.

Step 2. Click SIGN IN
It's in the middle of the page.

Step 3. Enter the account login information
Type in your Samsung email address and account password.

Step 4. Check the box " I'm not a robot"
This box is at the bottom of the page.

Step 5. Click SIGN IN
A list of saved Samsung phones and tablets will be displayed.

Step 6. Select your device
Click the phone you want to lock to select it.

Step 7. Click LOCK MY DEVICE
This option is in the pop-up menu.
This option can be found on the left side of the page

Step 8. Follow the instructions shown on the screen
You may need to enter information to display on the lost phone screen or set a password, depending on the device settings.
As a final step to protect your data, you can delete your phone data by selecting your device, clicking on the option “ WIPE MY DEVICE ”, and follow the prompts displayed on the screen.
Part 4 of 4: Contacting the Authorities

Step 1. Contact your cellular service provider
If you think your phone has been stolen, you should contact your cellular service provider immediately. The provider can turn off your number so that thieves can't use your phone to make calls and send text messages. The provider can also provide you with the IMEI number of the phone you need to make a complaint or report to the police.

Step 2. Call the police in your city
Visit the police station in your city or call the non-emergency number and report your loss. Provide as much detail as possible, and make sure you have your phone's IMEI number as the police will need that number. This step will not only help you get your phone back, it will also allow you to file an insurance claim and prove that you don't have your phone when it's charged suspiciously.

Step 3. Call the insurance service if necessary
If you insure your cell phone, start the replacement process as soon as you get a reference number from the police. Contact the insurance company to find out directly the instructions for the submission process.