Some Equipment Were Stolen

Hi, so last month I arrived back at my apartment to see that someone had broken into while I was gone and stolen some of my things. This includes the Xfinity bag, which had the yellow cable inside along with the box that my equipment came in. That was the only thing that was stolen-- I still have my Flex streaming device and my internet modem/router fortunately.  I think the yellow cable that was stolen was a coaxial cable. 

I was wondering, how do I report this? When the times comes for me to return my equipment-- what will happen? As I do not have the box or the yellow coaxial cable anymore. 

Thanks!