Browser Doesn't Recognize Icons Of FontAwesome

There is a problem with me that the icons is not showing in the browser. I can not able to find out that my browser doesn't have the Fontawesome font but even not showing when Internet is connected Please anyone can help me for this.

.checkbox {
  padding-left: 20px; }
  .checkbox label {
    display: inline-block;
    position: relative;
    padding-left: 5px; }
    .checkbox label::before {
      content: "";
      display: inline-block;
      position: absolute;
      width: 17px;
      height: 17px;
      left: 0;
      margin-left: -20px;
      border: 1px solid #cccccc;
      border-radius: 0px;
      background-color: #fff;
      -webkit-transition: border 0.15s ease-in-out, color 0.15s ease-in-out;
      -o-transition: border 0.15s ease-in-out, color 0.15s ease-in-out;
      transition: border 0.15s ease-in-out, color 0.15s ease-in-out; }
    .checkbox label::after {
      display: inline-block;
      position: absolute;
      width: 16px;
      height: 16px;
      left: 0;
      top: 0;
      margin-left: -20px;
      padding-left: 3px;
      padding-top: 1px;
      font-size: 11px;
      color: #555555; }
  .checkbox input[type="checkbox"] {
    opacity: 0; }
    .checkbox input[type="checkbox"]:focus + label::before {
      outline: thin dotted;
      outline: 5px auto -webkit-focus-ring-color;
      outline-offset: -2px; }
    .checkbox input[type="checkbox"]:checked + label::after {
                content: "\f00c";
                font-family: 'FontAwesome'; }
    .checkbox input[type="checkbox"]:disabled + label {
      opacity: 0.65; }
      .checkbox input[type="checkbox"]:disabled + label::before {
        background-color: #eeeeee;
        cursor: not-allowed; }
.checkbox-primary input[type="checkbox"]:checked + label::before {
  background-color: #fff;
  border-color: #adadad; }
.checkbox-primary input[type="checkbox"]:checked + label::after {
  color: #fff; }

<div class="checkbox checkbox-primary">
        <input id="checkbox2" type="checkbox" checked="">
               <label for="checkbox2" >
                     Primary \f00c
               </label>
</div>
<i class="fa fa-camera-retro fa-lg"></i> fa-lg