Check your body scales in the parameters menu first. Sometimes these get shrunk to 0%.

If not, then you have to edit the cr2 to reference the correct obj file. If you don't already have it, get notepad++ (it's free).

There are two lines in the cr2 that need to be edited. They both start with 'figureResFile' You'll see the first one as soon as you open the cr2. Change the rest of that line to whatever the correct path to the obj is. So, for example, 'figureResFile :Runtime:Geometries:necklace.obj'

Then scroll down until you find the 2nd 'figureResFile' line and change it there too. Then save the cr2. Make sure you save under a different name so that you don't lose your original file.

If that is the problem then the necklace should load correctly.