BSNL / CellOne SIMcard — my bsnl sim card blocked by puk

Address:

Bareilly, Uttar Pradesh

My mobile no. is [protected] and my sim card no. is[protected]...My problem is very small........
Day before yesterday when I was going t make a call suddenly my cell was switched off and when i switched on it. It was displaying that my sim card has been rejected and it also wants me to enter a PUK code.Actually I don't that is a PUK code that's why I do not enter any number and my most precious numbers are also deleted from it.......Please help me!!!!!!!