Can anyone help me with my iphone problem?

So, I bought an iphone about two weeks ago, and just now, it shut down without warning. It won’t turn on unless I plug it into an outlet charger. When it turns on, it can’t find a signal, has no wi-fi, I can’t send or receive calls or texts or basically do anything with it. I’ve never had an iphone, have no idea what’s going on, and would appreciate any help I can get! I’m hoping someone has experienced this before! :/