I'm very sorry to hear that you're receiving communication from PayPal in a different language. Is your account also showing information in that language? If so, please contact customer support to request that they get the settings changed back, and also look to see if there was any suspicious activity in the account that caused the language setting to change. If there were any unauthorized changes or transactions, a representative can help get that ironed out. You can reach customer support by Facebook, Twitter, or phone or email.
Once the settings have been restored, please make sure to clear your browser's cookies and cache to make sure that there are no stored cookies or cached pages that might cause the settings to revert.
I hope this helps!
If this post or any other was helpful, please enrich the community by giving kudos or accepting it as a solution.