Microsoft Word due to this error, failed to launch Microsoft Word

I cannot access Microsoft Word due to following error, What should I do to resolve this?

Failed to launch Microsoft Word. Please make sure Microsoft Word
is installed. Here is the error message:
Could not load file or assembly ''Microsoft. Office. Interop. Word,
Version=11. 0.0.0, Culture=neutral,
PublicKey Token=71e9bce111e9429c'or one of its dependencies.
The system cannot find the file specified.
