Open Office is a free MS Office clone. It runs in MS Windows, Linux, freeBSD, and MacOS. The web site is http://openoffice.org . It can read and write MS Word and Excel formats. It may be able to read PowerPoint but I don't use that. It can also write PDF files.
My first tip is finding single spaces after a period. In OO start the find via the menu or <ctrl>f . Select the check box - Regular expressions. In the search for box enter - \. [A-Z] . That is back slash, space, open brackets, capital A, dash, capital Z, close brackets. If you select find all, then all instances of a period followed by a single space and a capital letter will highlight in your document. Change the period to a question mark or quote and you will find those. Put in three spaces and you can find those.
Is this useful? Should I continue these tips? Do you have any problem in particular that you can't figure out how to fix? Please let me know.