There will be a time when something goes wrong with your business. A missed deadline, a late delivery, a broken computer. When these things (or others) happen, it feels like a disaster, and there is nothing you can do.
Except there is something you can do. Stop. Stop thinking negatively, take a minute and breathe. You have enough within you to overcome these little barriers to success, because that is all they are, little barriers.
A good client will understand if you call them in good time and explain what has happened. Be honest with them and yourself. A late delivery can be rescheduled and computers can be fixed, or at worst, data can be retrieved. There are solutions for most problems you could face and you are capable of facing and overcoming them.
Take each obstacle as an opportunity to learn and move forwards, not backwards. This can only make you and your business stronger.