Hello Shashi,
The University conducts term-end examination twice a year i.e., in June and December. You can take the examination after completion of the course. Whenever you are repeating examination you can appear either in June & December. In case you fail to get a passing score in the Term-end Examination, you will be eligible to reappear at the next Term-end Examination for that courses as and when it is held, within the total span of the programme.

For more information you can click on the link below:
http://www.ignou.ac.in/ignou/aboutignou/school/soms/programmes/detail/132/2

Hope this helps,
Good Luck!