Need a confidence

I had a job interview with a company today. I felt that they need someone who is really communicative in English and sadly I couldn't tell them I'm a that kind of person with confidence. I often think I have failed or gave up many things to do because of lack of confidence so I want to try hard to learn more about everything to have more confidence.
Another worry is that I found a bad tooth again even though I've been taking a good care of my teeth. I need to find a good dentist. Today was not good day for me feeling down.