Pattern Swatches Have Disappeared after Update

I am a pattern designer and rely heavily on being able to apply the patterns I've created to shapes using the swatches menu. I recently updated to the latest version of Illustrator. Since then, I've noticed that patterns I've created & saved in Illustrator are no longer present/accessible in the swatches menu of a given file (and neither are the colour swatches I've saved, for that matter). This means I can no longer draw a shape and fill it with a pattern I had created. Any suggestions on how to restore these swatches without having to re-design hundreds of patterns? Thanks in advance for any help you can provide! 🙂