Answer:
In any of the four programs below:
1) Choose File>Open
2) Open the Image you want to have Inverted or Reversed
3) Depending on the program you use, use one of these -
A) in MS Paint (Start>Programs>Accessories>Paint)
Choose Image>Flip/Rotate
B) in many versions of Adobe Photoshop
Choose mage>Rotate Canvas>Flip Canvas Horizontal
C) in many versions of Adobe Photoshop Elements
Choose Image>Rotate>Flip Horizontal
D) in many versions of the free program GIMP (at GIMP.org)
Choose Tools>Transform>Flip