For example, a 10 yr bond (in India) has a coupon of 8%, maturity date of 12-Nov-2020, and Maturity value of INR 10,800. It is trading at 9750 now. How do I compare returns from selling it now versus holding it to maturity, assuming I bought it for INR 5000 during the initial offer period?
You can separate the past from the future in the following way:
It has a value of 9750 now. Anyone who bought it would pay 9750 for it now and get 10800 in roughly a year. That means they get about the 1.107 fold, i. e. it has a profit of about 10%.
The same happens to you if you keep it vs. if you sell it: 9750 now or 10800 in roughly a year? Makes a difference of 10%.
If the coupon is payed annually and not included in the proce of 10,800, you'll additionally get the coupon.