To update your LG Realm, go to Settings. Find General, then look for an Update Operating System option. Select the most recent upgrade and wait for it to download. Often, you will be prompted to restart your phone after an update has been downloaded.
If your headphones don't seem to be the problem, check the audio jack for debris. Attempt to remove any debris by blowing air into the jack. If this doesn’t work, look at the phone's Audio Settings to make sure that the audio jack is enabled.