CrossPlatformInput namespace

I am new to Unity and it is not letting me run any projects because of a scripting error. I tried redownloading unity but the error still occurs. This is what the error says at the bottom of the screen:

Assets/_CompletedAssets/Scripts/Player/PlayerShooting.cs(2,25): error CS0234: The type or namespace name ‘CrossPlatformInput’ does not exist in the namespace ‘UnitySampleAssets’. Are you missing an assembly reference?

Please can I get some help. Thanks.

Find the CrossPlatformInput file, identify which namespace the class is declared in, and, at the top of the PlayerShooting.cs script, add :

 using NameSpaceWhereCrossPlatformInputIsDeclaredIn ;

tl;dr

add using UnityStandardAssets.CrossPlatformInput; at the top of your PlayerShooting.cs script

Just open the PlayerShooting.cs to edit, and replace using UnitySampleAssets.CrossPlatformInput; with using UnityStandardAssets.CrossPlatformInput;