What can I do when my battery isn't showing on my top bar?

I just got done restarting a friends iPhone 5s, and right when we were done, she left. Then out of nowhere my computer restarts, and restarts, and restarts. Once it was done restarting, I tired to see why my battery sign wasn't working, and I tired trying the battery sign back on , it wouldn't let me. it just have the battery sign charging for a spilt second, and I'm not even connected to a power source. Please I need answers this worries me a TON!