Hello,

Seems like you have added this CSS on your site

h2 {
    font-size: 30px;
    display: none;
}

Please remove the display:none part of the code which is making your h2 titles to disappear.

If you cannot find and remove the required code, you can always add the below given CSS code

h2 {
    display: block;
}

Hope it helps.
Best regards.