My phone lost service...and won't come back!

My i425 is only 3-4 months old. It's only been dropped once but that was a carpeted floor. The problem is the other day my phone lost service like it usually does in certain rooms of my house but instead of it coming back on a few minutes later, its been out ever since. I did the master reset that didn't work. I even took my sim card out and put it in another phone (an i425) and found that its not a problem with my account. So what can I do to either solve my problem or should I just toss it out?