My book world edition 1 (blue rings) - bizarre....no longer mapped as a networked drive?

I just have a new Windows 7 based PC.

The external hard drive (My Book World Ed 1) was installed through a router and wireleslyconnected to my old Windows XP based computer.

When I turned on the new computer, it automatically found the external hard drive on my “local home network”.

Then one day it just didn’t find it and now it isn’t visibl to any computer that logs on to my “local home network”.

I have all my photos and iTunes music stored on this hard drive and now I can’t access anything…PLEASE HELP!!