When you mute someone’s status it doesn’t disappear, but it goes in the section “Muted updates”. “Muted Updates” is the last section on the status page. First section is “Recent Updates”, second section is “Viewed Updates” and third & last section is “Muted Updates”.
So scroll down to “Muted Updates” section, press the muted contact’s status and click on “Unmute”.
How to unmute anyone’s status when their status has disappeared on WhatsApp - Quora