I have received messages in German language when I log in e.g. when I want to login my ymail on first page, username and pw is in german.
I'm sorry to hear you're experiencing this issue and I'd like to look more into it to help, please contact us on Twitter at @YahooCare or on Facebook at our Yahoo Customer Care page. If you do not have a social media account, we are available at help.yahoo.com through the ''Contact us'' link.
Mahmood Sufyan commented
Please help thanks