Perhaps you want to try the search “free French books online.” Italian anyone? Free children’s content is especially easy to find.
I’d recommend paying for the right book, though. Do you have a special book you have read and reread in English? Getting its counterpart in a language you want to review gives you a head start at retrieving all those long lost words you buried deep in your gray matter. You probably remember that special book well enough so that the text will give you clues to help you translate as you go along. If you are lucky, your book’s in a popular series. Harry Potter has been translated into more than 70 languages. Stephen King books have strong international popularity as well and can be found in Azerbaijan, Norwegian, Turkish and a long list of other tongues.
Stuck at home? I suggest a nice hot cup of tea and Le Hobbit, Der Kleine Hobbit, or 호빗 (Hobit), possibly with your English copy of The Hobbit alongside you. Maybe slice up some apples and cheese to go with your tea? Or raid the chocolate drawer? Treat yourself anyway.