How do I search for content inside a file?

[vickyblueeyez.livejournal.com]

 In a fic finder community, someone was looking for recs. I had a fic to rec, knew I saved it but don't know the title. I could look through all the saved fic PDFs that I have but I have over 650. Is there a program or anything where I can find things inside of documents? I've tried regular windows search and 'file contents' search. Both came up empty. Any ideas? I want to be able to search and not have to open every pdf file. Thanks