First off, please do not call yourself "loser." You're not a loser; everyone has times of hardship.
Second: Rehearse answers to potentially tricky questions. You can find tips on this all over the internet. Just do it.
Third: Relax and be your charming self. If someone calls you in for an interview, you almost always have the job unless you throw it away. (If an organization interviews 5 million people before filling a position, they are just nuts, and you don't want to work for them anyway. Experience speaking here.)
They know you can do the job and are willing to accept you despite any shortcomings in your resume. What they are trying to find out is if they like you enough to work with you: Do you have a firm handshake? Are you a nice person they'd enjoy working with every day? Are you self-disciplined? Are you an adult who can pull your own weight? Do you take pride in your work? That's all they want to know. Unless you're in a field like brain surgery or engineering, it's mostly social.
Go get that job.