A player may take unplayable ball relief using one of the three options in Rule 19.2a, b or c, in each case adding one penalty stroke. 

Relief options being:

• Stroke-and-Distance Relief
• Back-on-the-Line Relief
• Lateral Relief

The player may take stroke-and-distance relief under Rule 19.2a even if the original ball has not been found and identified.

But to take back-on-the-line relief under Rule 19.2b or lateral relief under Rule 19.2c, the player must know the spot of the original ball.