Editing a saved body

Hello,

A bit of a difficult one. Basically i have been working on a set of about 4 parts within one parts document (each saved as a seperate body). I had created a second copy of my document, which i have been editing. At some point i accidently deleted one of my parts from the new document without realising, and continued to work unaware. When i realised that the part was missing, i simply inserted the part and realigned it. Simple! Until it comes to editingthe particular body. I wanted to make some adjustments to some rads. It seems i can add new features but cannot make any changes to the body???

Any ideas why this is, and how i can make it editable again?

Cheers,

Luke

SolidworksParts And Features