If you find that your developer tools are open but off-screen, then easily get them back with the following keyboard Shortcut:-

CTRL+SHIFT+D

Hey-presto the Chrome Developer Tools reappear at the bottom of the Chrome Browser.

Accessing DevTools

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