Since you are from India, you know once paid, nobody likes to refund money and since it is an institution you must cite strong reasons for the refund. Unfortunately, you have not given any reason. So I have assumed certain reason which may not true but must mentioned in your letter. This is how it looks:
Sub: Refund of fee paid for admission
I have deposited on--------a sum of Rs-------/- (amount in words) with your Institute towards fee for admission which is scheduled to take place on the 16th August’2009.In the meantime due to certain unexpected development I am compelled to move from this town to a distant place. Consequently, I shall have to face a lot of inconvenience, if I take admission in your institute.
Under the circumstances, I have no other alternative than to seek refund of the fee paid by me. I hope you will be gracious enough to consider my request and pay back the amount at the earliest.