Internet Explorer 8 Developer Tools not displaying

Not related to the window issue, but in some companies, this could be due to policies. In such cases, at least for me, it worked after modifying the registry like this

HKEY_LOCAL_MACHINE > SOFTWARE > POLICIES > MICROSOFT > INTERNET EXPLORER > IEDEVTOOLS

and then modifying the DISABLED value to 0, which was 1 for me previously.

If you are on Windows 7, Windows Key + Up Arrow Key will maximize the window.

How do I get a window back on the screen when it moved far, far away?

From the article:

Switch to the application, say by clicking on its taskbar button or by Alt+Tab'ing to it. Then type Alt+Space to call up the System menu: You should get a window floating at the edge of the screen. Type M to select Move, then press an arrow key to enter Move mode.

Additional remark by @WebSolProv:

It would appear that something happens with IE that causes the developer tools window to be shrunk to the height of the header bar and width of about 2 inches. By using this solution you can then move the the window into view and enlarge as usual.