Η application Office Search will help you find text within Microsoft Office, archives RTF and more generally than all text files.
You can search Microsoft Office (Word, Excel, Power Point), LibreOffice (Writer, Calc, Impress), Visio, RTF but also in ASCII text files (TXT/CSV/ MD/HTML/PHP etc.). 
For all other files it will use fuzzy logic to check if the file is text or binary. If you do not remember the file name, enter some of the text in the content, and it will display the contents of the matching files. The application runs on Windows 7/8 and 10.
Even if your folders are not meticulously arranged, you can easily find your documents as long as you remember a little of what they say.
If you know that certain file types are ASCII, you can add these file types to the config file so that you can search the application.
It supports Unicode / non-English characters, so you can also use the application for text in Greek.
