Do you mean  the Library dropdown does not show up at all, or  that there is nothing there about the Kobo Touch?
For non-DRM books, I think you should just be able to copy them to the Touch using Windows Explorer or similar.
For DRM, direct file copy should also work (at least, it does on many eReader devices),
You can only read the copied books once the Touch has been registered to the appopriate AdobeID,
but that registration is only needed once.
There have been quite a few issues with ADE2.0 which were not present in 1.7.2,
it may be that ininstalling V2.0 and installing that will work better for you.
Version 1.7.2, it is a little difficult to find, available on Adobe site for Windows and for Mac.