Want to have my old Gmail account back & not the newly created

Hello,
as my computer has been up graded to windows 10, & as i tried to open my gmail account by mistake i followed some instruction& by mistake a new account has opened due to which iam not able access my old gmail account, Actually i want to have have the same old g mail account ¬ the newly created as all my email are in the old gmail account. So how to have & use the same old Gmail account :----brirani ***@***