What do I do if I bought something online and the company won't respond?

I bought a knife over 2 weeks ago. The site says 7–10 business days…I called when it’s been a week and left a message. The site says they’ll respond within 24/7 email/calls. No message after 1 week. 2nd week, left another call…and a email. Still no answer!

I’m getting angry, maybe I’ve been ripped off. It’s almost 3 weeks now.