Share social icons: Twitter icon not showing

Hi there, first the share social media icons weren’t showing at all. Then I found the following code in an older thread – share via LinkedIn, Facebook and Mail the icon is showing, but not Twitter icon (see link below)? Do you have any solution for this one? Thanks a lot, Ursula
/*———————————–
enfold social media icons fix
———————————–*/

}
.social_bookmarks_twitter a::before, .av-social-link-twitter a::before {
font-family: ‘entypo-fontello’;
content: ‘’;
}
.social_bookmarks_facebook a::before, .av-social-link-facebook a::before {
font-family: ‘entypo-fontello’;
content: ‘’;
}
.social_bookmarks_linkedin a::before, .av-social-link-linkedin a::before {
font-family: ‘entypo-fontello’;
content: ‘’;
}
.social_bookmarks_pinterest a::before, .av-social-link-pinterest a::before {
font-family: ‘entypo-fontello’;
content: ‘’;
}
.social_bookmarks_tumblr a::before, .av-social-link-tumblr a::before {
font-family: ‘entypo-fontello’;
content: ‘’;
}
.social_bookmarks_reddit a::before, .av-social-link-reddit a::before {
font-family: ‘entypo-fontello’;
content: ‘’;
}
.social_bookmarks_vk a::before, .av-social-link-vk a::before {
font-family: ‘entypo-fontello’;
content: ‘’;
}
.social_bookmarks_gplus a::before, .av-social-link-gplus a::before {
font-family: ‘entypo-fontello’;
content: ‘’;
}
.social_bookmarks_mail a::before {
font-family: ‘entypo-fontello’;
content: ‘’;
}
.social_bookmarks_dribble a::before {
font-family: ‘entypo-fontello’;
content: ‘’;
}
.social_bookmarks_youtube a::before {
font-family: ‘entypo-fontello’;
content: ‘’;
}
.social_bookmarks_instagram a::before {
font-family: ‘entypo-fontello’;
content: ‘’;
}
.social_bookmarks_vimeo a::before {
font-family: ‘entypo-fontello’;
content: ‘’;
}
.social_bookmarks_whatsapp a::before, .av-social-link-whatsapp a::before {
font-family: ‘entypo-fontello’;
content: ‘’;
}