Use Binder Clips to Replace Broken Keyboard Feet
They make great cable organisers and phone stands, but the humble binder clip can also fix things that are actually broken, too.
In this case, it's those little flip-out "feet" on the bottom of most keyboards. Just take the metal wings off two clips, and replace the feet by squeezing the those wings into their place. If nothing else, it's a lot cheaper than replacing the keyboard.