This is the time when you type words in order to make your post understandable, posting code (without code tags) and hoping that your title is sufficient, often is not.

What you "appear" to be asking, is that when the user selects the last item in the listbox, that you actually select the first item. This would mean that your user can never select the last entry. Is this what you want? I can only guess what you are trying to do is create a roll-over method?

The first place you should check is the documentation, which has a list of all the properties of a listbox control, of which one is items, which has a count property. As the Index is 0 based, you would have to -1 from the value.
Code:
ListBox1.Items.Count -1