There is no button or menu option to change right to left direction in Windows 7 Wordpad. In toolbar you can only find alignment buttons which is not useful in this case. But still the worpad support windows global hotkey for switching between right-to-left and left-to-right directions.
In any paragraph in Wordpad you can use "Control + Right/Left Shift" to change direction.
to set a paragraph direction to:
Right to left: "
Control+Right Shift"
Left to right: "Control+Left Shift"