We encountered an error and I need some help؟

Could not start compilationApplicationException: Unable to find csharp compiler in E:/Unity 4/Data/Mono\lib/mono/unity_web
Download New Version 4.1.3f3 I feel I’m in trouble when I download it, I get this error
If anyone thinks that the problem was caused by a specific file but allowed him to send me the file?

Consol:

UnityEditor.Scripting.Compilers.MonoCSharpCompiler.GetCompilerPath (System.Collections.Generic.List`1 arguments) (at C:/BuildAgent/work/7535de4ca26c26ac/Editor/Mono/Scripting/Compilers/MonoCSharpCompiler.cs:57)
UnityEditor.Scripting.Compilers.MonoCSharpCompiler.StartCompiler () (at C:/BuildAgent/work/7535de4ca26c26ac/Editor/Mono/Scripting/Compilers/MonoCSharpCompiler.cs:35)
UnityEditor.Scripting.Compilers.ScriptCompilerBase.BeginCompiling () (at C:/BuildAgent/work/7535de4ca26c26ac/Editor/Mono/Scripting/Compilers/ScriptCompilerBase.cs:40)

2 error:Internal compiler error. See the console log for more information. output was:

1 warning : Compilation failed because the compiler couldn’t be executed!

Your Unity installation is corrupt. Please try uninstalling Unity and reinstalling the latest version. If that doesn’t work, please post back here and send a bug report to Unity.