convertible issue----my parcel shelf was lying in my trunk so I put in back into place but it isn't placed right, now I can not move it at all. Does anyone know how to remove it so I can try to set it back it correctly?

 

Not sure what a "partial shelf" is? Can you post pictures?

 

I believe the OP meant "parcel" shelf. The deck below the rear window. Yes, I chuckled too.

 

Well, if you have identified the Parcel Shelf correctly...i.e. the matte black, plastic, panel immediately behind the rear passenger seats...I would say be VERY careful about trying to "re-attach" or "place it back" in position. That Parcel Shelf is connected to, and sequenced into the entire top operation. I highly doubt that an owner can resecure a loose or disconnected Parcel Shelf and return the highly complicated top to normal operation.
Now...if by "Parcel Shelf" you mean the Seperator in the trunk...the moveable, hinged, two-piece unit that moves manually up and down at the very rear of the trunkspace, well, THAT piece IS meant to be manually moved by the owner every time they want to place items in the trunk that would preclude top stowage. The Seperator needs to be in the "up and locked" position, with nothing forward of it in the trunk BEFORE top retraction.
Is the Seperator the item you are having trouble with? Or is it actually the Parcel Shelf?
IF it is actually the Parcel Shelf, you would need Infiniti Maintenance to secure it back in to its original, proper, and SAFE position...I am not even sure HOW it would or could "just fall out" and into your trunk. THAT is weird. If your G37 is a 2010 or later, it would still be under factory warranty and the repair would be free.
Good luck!