Listing details are available for 90 days.
They will be available in the sold section of 'my ebay' for 60 days.
Between 60 and 90 days old, you could access the item details to relist by finding the items on your Ebay invoices.
If you have selling manager, (it's free to subscribe), they will show in the sold section there for 90 days.
For future reference, if you create your listing using turbolister I beleive that you can save them indefinitely.
Info here:
http://pages.ebay.co.uk/selling_manager/
http://pages.ebay.co.uk/help/sell/turbo-lister-ov.html