I can only enter capital letters.

There are possibilities as follows.

  • Caps Lock is ON
    To switch ON/OFF Caps Lock, hold down the [Shift] key on the keyboard and press the [Caps Lock] key.
  • “All caps” option is ON in Microsoft Word font setting
    The “All caps” option is toggled ON/OFF with Microsoft Word keyboard shortcut [Ctrl] + [Shift] + [A]. If you encounter such a problem on Word, you may have pressed this keyboard shortcut without noticing.