It says "This book has been ordered" but I haven't ordered anything

A book is locked once it is in your basket or has been bought, so that what you are about to pay for — or have already paid for — cannot change underneath you. Nothing has been charged unless you have been through checkout. Select Create a copy and you get an editable version to work on, while the original stays exactly as it is. Then add the copy to your basket and remove the older line.

Where to find it: The window that appears when you open a locked book.