You should be able to find it in your purchase history, in the archived section. 

Click on Purchase History in the dropdown menu for My eBay, then check the Archived box, and it will display all purchases from  2012 (you can look through up to 3 years purchase history there). 

So i bought a stereo about 9 months ago. I have gone to my feedback to find when I bought it as I wish to buy another one from the same seller. But now none of my feedback has a description. SO what do I do now.

In addition to LOTB and D*G's advice, you can also go into your PayPal account (if you bought it using PP) and search Purchases with the date range of around 9 months ago. It should show a number or transactions and the stereo should be listed in there, with the seller's name listed under "Seller's ID."