Here's something to try...perhaps the Tools palette location got stored in the LabVIEW INI file with some funky location, such that it is showing up, but not within the visible bounds of the screen. I'm not sure what the INI entry would be, but it's probably something human readable, like "ToolsPalleteLocation="2000,2000". If you see an entry like that, delete it and restart LabVIEW. But if you don't see anything immediately obvious, you could close LabVIEW, delete (or rename) your LabVIEW INI file, relaunch LabVIEW, and see if your Tools palette shows up again. If so, then it's definitely something fishy in your INI file.
Also, I seem to recall from my days long long ago in the AE department that there might be a KnowledgeBase entry, or a previous Dev Exchange post, on this issue. So if my suggestion is no good, try checking those resources.
Good luck,
-D