Try your Activity Log > in left column select Likes filter--then below that select Pages & Interests subfilter > as long as you didn't delete the story about the Like from your Timeline it may list things back as far as 2006 (use the year in the right column to scroll back)--there will be an icon off to the right of
How do you Unlike pages on Facebook quickly?
For saving time go to the pages feed section and click on the "v" that appears on the right top corner of any feed and then unlike the page. You can also unlike a page quickly by going to the interest section and then into the liked pages under them, that is an even quicker way to get rid of the useless liked pages.
How do you see your liked pages on Facebook Mobile?
Go to your profile page (click your name, not "home"), then scroll down to. Then, on the banner under your profile photo, click "more", then "likes". Then on the banner that appears under THAT banner, click "more" again. All of your currently 'liked' pages will be in this list.