If you find that your developer tools are open but off-screen, then easily get them back with the following keyboard Shortcut:-
Hey-presto the Chrome Developer Tools reappear at the bottom of the Chrome Browser.
|Access DevTools||On Windows||On Mac|
|Open Developer Tools||F12, Ctrl + Shift + I||Cmd + Opt + I|
|Open / switch from inspect element mode and browser window||Ctrl + Shift + C||Cmd + Shift + C|
|Open Developer Tools and bring focus to the console||Ctrl + Shift + J||Cmd + Opt + J|
|Inspect the Inspector (undock first one and press)||Ctrl + Shift + I||Cmd + Opt + I|
This comes direct from Google Official Keyboards Shortcuts Reference