Hello,

Yes, if you do hard work you can pass in your class 12th i could have answered more in a detailed way if you have told in which subject you have failed and what stream you are of science,Commerce or Humanities but overall i would say only hardwork can help one to succeed in there life and also i would like to tell you failing in one exam won't led to repeating the class but you can still give exam to improve your marks.

Hope this helps you,

Thank you