my class 12th marksheet has not yet arrived. but I have to carry it to nodal centre for verification. what's the remedy
Don't worry,
you write an application and get it signed by you school authorities and take that application in place of mark-sheet.
Many students there would must be dealing with the same problem.
They'll provide you a due date for submission of the mark-sheet.
Don't worry about that.
Best of luck.