Problem starting a project

hi all, today when i tried to open an existing solution i had this message: "Project could not be opened because the Microsoft Visual C# .NET compiler could not be created. A wrapper assembly is not registered for this type library" one time also appeared: "Project could not be opened because the Microsoft Visual C# .NET compiler could not be created. Please re-install Visual Studio" Any solution??? I worked whit this solution until yesterday with no problem. Now i can't open any solution or project. Thakns