Couple years late but maybe people still come up with the issue.
Simple as that: While building you might've used the Shift+Alt Key at the same time to move objects and multiply them. This also changes your Keyboard Layout Settings(Language and Country Keyboard Layout)
Solution: Either you press Shift+Alt to get the selective window and choose your original keyboard layout that you set on windows
OR: you go to your bottom right screen, flip open your taskbar if it's hidden, go to the selective window which should state your current language/layout as seen in mine as "ENG"
Change it here back to your ORIGINAL SETTING IN WINDOWS(Default Language/Layout)
and there you go. You can now again move with WASD