The dreaded lost file syndrome: You know that somewhere on your hard drive, the file you seek is happily sitting, awaiting you. But you just can’t find it, and you can’t even remember the name of it.

Now what? If you’re a Windows user, replace the painfully slow built-in search tool with the free Windows Search from microsoft.com. The add-on can dig up e-mail messages, attachments and documents of just about any type. You can also try a third-party system, many of which are free. Google Desktop Search, for example, marries your local PC file system with the Web-based Google search system, allowing you to find virtually any kind of file, and gives results in a familiar Google display. Another option if speed is your main concern: Copernic Desktop Search, which can complete most searches in less than a second. Keep in mind that all of these tools let you search within the text of a file as well.

Mac users can try the built-in Spotlight feature, which has lots of power and hidden capabilities, including searching by type, creation date and more. Or, for $60, Leap lets you tag files so you can run complex searches (say, “Word files that talk about South Africa” or “photos that include Mary”) to track them down later.