Apk file isn't building?,Apk file isn't buliding

While Buildind apk file unity shows "Building player Failed And shows following errors:

UnityEditor.BuildPlayerWindow+BuildMethodException: 3 errors at UnityEditor.BuildPlayerWindow+DefaultBuildMethods.BuildPlayer (BuildPlayerOptions options) [0x00207] in C:\buildslave\unity\build\Editor\Mono\BuildPlayerWindowBuildMethods.cs:172 at UnityEditor.BuildPlayerWindow.CallBuildMethods (Boolean askForBuildLocation, BuildOptions defaultBuildOptions) [0x00050] in C:\buildslave\unity\build\Editor\Mono\BuildPlayerWindowBuildMethods.cs:83 UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

Build completed with a result of 'Failed' UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

Assets/Standard Assets/Utility/SimpleActivatorMenu.cs(10,16): warning CS0618: UnityEngine.GUIText' is obsolete: This component is part of the legacy UI system and will be removed in a future release.'

Assets/Standard Assets/Utility/ForcedReset.cs(6,27): warning CS0618: UnityEngine.GUITexture' is obsolete: This component is part of the legacy UI system and will be removed in a future release.'

Please sir tell me how to solve this problem I will be thankfull to you.

,while building apk file unity says "Building player Failed" And shows following errors: **UnityEditor.BuildPlayerWindow+BuildMethodException: 3 errors at UnityEditor.BuildPlayerWindow+DefaultBuildMethods.BuildPlayer (BuildPlayerOptions options) [0x00207] in C:\buildslave\unity\build\Editor\Mono\BuildPlayerWindowBuildMethods.cs:172 at UnityEditor.BuildPlayerWindow.CallBuildMethods (Boolean askForBuildLocation, BuildOptions defaultBuildOptions) [0x00050] in C:\buildslave\unity\build\Editor\Mono\BuildPlayerWindowBuildMethods.cs:83 UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr).

And

Build completed with a result of 'Failed' UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

Assets/Standard Assets/Utility/SimpleActivatorMenu.cs(10,16): warning CS0618: UnityEngine.GUIText' is obsolete: This component is part of the legacy UI system and will be removed in a future release.'

Assets/Standard Assets/Utility/ForcedReset.cs(6,27): warning CS0618: UnityEngine.GUITexture' is obsolete: This component is part of the legacy UI system and will be removed in a future release.'**

Please tell me how can I solve this problem.I will be thankfull to you.