Could you answer some questions please? Without the answers I have no way of saying whether you're right or not.
1. Why have you changed the function from the prototype? Remember at the top you said "the prototype of the function should be ItemType ReturnLastItem();", but for some reason you've changed it to "ReturnLastItem (item,info)" (which is wrong on four counts: (a) there is no return type; (b) there is no type for item (and if this is a class member why do you want to pass it in as a new variable?); (c) there is no type for info (and if this is a class member etc); (d) it does not match the prototype you've been given.
2. What is length?
3. What is info?
And now a new one from your latest code:
4. What is MAX?
In terms of the other code you should add, remember the statement you made earlier: "the whole question says that we should add a member function ReturnLastItem () to the UnsortedType ADT". So it's not what code you should wrap around ReturnLastItem() itself, but what code you should insert ReturnLastItem() into. Do you have a source/header file for UnsortedType?