If you are using Android 4.4.2 Jelly Bean or earlier, you can upgrade to Lollipop using the following steps:

  1. Open the Settings app and navigate to the “About phone” section.
  2. Scroll down and tap on “Build number” seven times.
  3. The phone will automatically update to Lollipop when it reaches its build number of 7.0.x or later.