The SMS sign is missing. How can I get it back?

Taking vivo mobile phone as an example, the specific operation of retrieving SMS icons is as follows:

1. Find and open the settings on the phone desktop.

2. Find and click the application management option on the page.

3. Click All in the upper right corner of the page.

4. Slide down the page to find and click the SMS option.

5. Open the "Allow Notification" button to complete the specific operation of retrieving SMS icons.