i gave my father cellular balance of 10000 rupiah. But then my father gave me 10000 rupiah of real money to change for what i have given (the cellular balance). Is that okay?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad, sallallaahu 'alayhi wa sallam, is His slave and Messenger.

There is nothing wrong with your father giving you the value of the credit that you transferred to his cell phone. You transferred a value of 10,000 Rupees as you mentioned, and he gave you 10,000 Rupees in cash. Even if he gave you more or less than this amount, there is nothing wrong with it. This is because it (the credit) is a benefit and it is permissible to sell it for its regular price, or more or less than that; this is not like selling a currency with its similar kind.

Allah knows best.