Please see this page for the most common reasons why a PayPal payment may not be processed by E-junkie:
http://www.e-junkie.com/ej/trouble.paypal.completed-order-not-
processed.htm
If only one or a few sales failed to get processed, but most of your other sales since then have been processed by E-junkie just fine, then the most likely problem is that PayPal failed to transmit an IPN to our system confirming those particular payments. PayPal was having some IPN problems on the 20th in particular, which we posted about in our Service Status & Updates forum here:
http://www.e-junkie.com/bb/topic/3636
Since we depend on receiving IPNs to be informed about actual sales to process, there is nothing we can do if PayPal drops the ball and loses an IPN, which does rarely happen. For download purchases, you can use your Seller Admin > "Send free download link" to satisfy concerned customers.