Not sure why my scale area has turned grey and is not allowing me to zoom in or out?
Oftentimes, the map scale is grayed out because the data frame doesn't have a defined coordinate system. You can check this by opening the data frame's property page (right click in the map or "Layers" in the table of contents and select properties). Select the Coordinate system tab. The current coordinate system is listed. If it's Unknown, you'll need to set it.
This also happens if your data frame is set to a fixed scale or fixed extent.