There must be a way! Why on earth can I only find an option to 'unlock all on spread' rather than just a single item? What sense does it make to take this away? I can't be the only one with multiple locked items in a document only wanting to unlock ONE! If you wanted everything unlocked all you have to do is 'Select All' and then 'Unlock'... why did that need it's own command and to replace the simpler version? What a huge, time-consuming PITA to have to reselect the numerous items and re-lock them! I hope someone can tell me I'm wrong and that the single unlock is buried somewhere else... if not, maybe someone can explain the rationale for taking it away...
If you have Frame Edges showing, you can click on the small lock Icon on the object.
If not, you can still unlock individual objects from the layers pallet.
Locate the object(s) in the Layers panel and unlock it / them there.
Sorry it took so long to thank you for the helpful replies!