Userform Listbox

I am having two issues with my Userform List Box.  

1.  When accessing the User Form in visual basics, my list box shows properly and lists the data entries.  However, when I create a command button on my workbook to allow access to the User form, you are no longer able to see the list box.

2.  I have the list box coded so that when an previous entry is selected from the list box, it is loaded into the userform correctly.  However, when I then edit the data and save it back to the worksheet, it creates it as a new entry instead of replacing the original entry.   I do not know where to begin coding on this command.