I want to know how I can convert recharge card to money into my bank account
Yes, you can do that but the cost of such an operation would be 20% of the amount and the maximal amount is 500 naira. You can charge the card of your kid or relative (friend), then they go to the bank and the money is set on their account. Again, the fee is pretty high on such money transferring operations. Both Glo and MNT provide such services.