Make sure you imported FontAwesome correctly:
<link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.13.0/css/all.css"><link href="https://maxcdn.bootstrapcdn.com/font-awesome/4.2.0/css/font-awesome.min.css" rel="stylesheet">Make sure you don't keep the name of all the font families by using this (*). If yes, you can remove the font-family property.Make sure you import FontAwesome correctly indented.
#Take the code from your font awesome