To help you, there is a free add-in for Microsoft Office (2010, 2007, and 2003) that will give a complete report on grammar, spelling, plagiarism and vocabulary mistakes.
The very simple to use add-in Grammarly analyze your documents online and instantly give a detailed report on it.
However, to solve your problems, you need to subscribe and pay. Even so, you can make sure that your document is free from grammar and spelling mistakes.
Grammarly Add-In requires Microsoft Office 2003, 2007 or 2010. Download the add-on at the source.