Thanks for reaching out here as I understand that this could be challenging. If you can sign into the account, I should be able to lead you through how to change it. I'll provide a screenshot with the step by step instructions to make it easier.
1. Click on the gear icon in the top right
2. On the left side halfway down is where you'll change the language
If you use the positioning of the page, it should be pretty easy to change back. Once you do, click on the security tab and make sure you update your password and security questions to resecure your account.