Only one on on my Sprint Samsung Galaxy 4G phone?

So I had been running out of batteries on my phone and kept turning it on anyways after it had automatically shut down. The four usual ons on my phone disappeared except the applications on. I was not surprised because I umed that happened just because my battery was pretty much dead and the phone would not have service so it took away my contacts, phone, and messages ons that are on the bottom of my screen. When I replaced the battery with a fully charged battery the on did not reappear and have not reappeared yet. I still only have the applications on at the bottom of my screen. I have the Phone, Messages, and Contacts button mixed in with all the other applications but they are not where they normally should be at the bottom of screen all the time.