Last year Sales Return after finalisation of BS

Dear Members,

How to book Sales returnin current FA year which is sold in previous or its previous FA year?

Example: -

In FA 2009-10, We have booked sale od Rs. 5000 and its COGS was Rs. 3000. And customer returned complete goods in FA 2011-12. What are the entry / Entries needs to be passed to adjust sales return transaction.