The return process is real simple if you have received an item that isn't as decsribed or damaged.
You open a return, then your seller should issue you with a pre-paid returns label.
If they don't, after 3 business days an option to ask eBay to step in appears, if you use that then eBay will either supply you with a label or simply refund you.
Once you close an eBay return you cannot re-open it or open another for the same order. What other case have you opened? A PayPal one?