What can be the best way to regain lost confidence when faced with untime failiures regarding studies or when something happens very unexpected which makes us lose confidence..

First of all please specify what happened...
Well let me assume the worst. Say , you failed one year...
What I have to say is just take it in your stride.
Face it. What I have to say from my experience is that a failure will only do us good. It helps us to reassess what we are and what we want. It help us to refocus.
Just be honest to yourselves... and you will not face the same situation again.
And there is no such thing as an 'untimely failure'. A failure or a pass is the result of our actions. You get whatever you qualify for. OK. Good luck!!

A failure is pointless only if we learn nothing from it. It's only through failures that we learn what it means to succeed. Celebrate your successes (we've all had some), and look unashamedly at your failures to see what you can learn from them so you don't repeat the same mistakes again.

Almost no one succeeds 100% of the time. Those who do succeed 100% of the time often have a hard time with failures. The most successful people in the world have failed over and over again before they succeeded; check out this list of six famous failures from Business Week. You might be surprised to find who's on the list.

Vasily