You are using Font Awesome incorrectly.
You must insert the icon in the form in which it is given on the official site, that is:
& lt; i class = "fab fa-vk" & gt; & lt; / i & gt;
& lt; i class = "fab fa-instagram" & gt; & lt; / i & gt;
& lt; i class = "fab fa-youtube" & gt; & lt; / i & gt;
Paste these lines inside
& lt; li & gt; and then it will work for you.
And in the future, look for the icon you want here , go to her page and grab the provided
& lt; i & gt; code for her.
The problem was that the vk icon belongs to a separate font and you need to apply
font-family to it: "Font Awesome 5 Brands";