Hi Alice, let’s practice together:)

In my experience, it depends on how well you knew the language and how much time has passed. If you got it to a high intermediate/advance level, you will likely always remember it to some extent. You may just need to practice to bring it back up. If you only got to a beginner level (esppecially low beginner), you'll likely have to relearn most of it if a lot of time has passed (several years). Thanks for the interesting question, Alice! :)