I've never been a fan of the search facility that's built into Windows.  It doesn't always find what I'm looking for.  Plus, if you want to be able to search the full text of all your files, rather than just the filenames themselves, you need to turn on indexing.  Which slows down your computer and takes up valuable hard disk space.  Which is fine if you use the search feature a lot, but not so useful if it's something you need only rarely.

My preferred solution for those moments where I need to search all the files on my hard disk for a specific word or phrase is a program such as "grep".  Grep is a well-known command that's built into Linux and Unix, but isn't part of Windows.  There are, though, a handful of free versions that do a pretty good job.

One that I've used over the past few days is Astro Grep, which you can find at http://astrogrep.sourceforge.net/.  It's a tiny 0.2 MB download, works on Windows XP and above, and is portable so it needs no installation.  It's also malware-free according to Web of Trust and VirusTotal.

To use it, extract the downloaded zip file and then run the .EXE file that's included.  Enter the search path (ie, the folder from which you want to start searching), as well as the file spec that you want to search and the text you're looking for.  Because grep programs don't create an index beforehand, searching can take a good few minutes, so make sure you narrow down the program's workload by specifying a suitable search path.  For example, if you know that what you're looking for is somewhere within MyDocuments, make sure you say so.

Once you've entered all the required data, just wait as your search hits gradually begin to appear.  That's really all there is to it.  So now there's no longer any excuse to say "I know that document is somewhere, but I just can't remember where".  So long as you can recall a couple of words from it, Astro Grep will find it.