lost email

I was recently asked by Xfinity to migrate my email account over to the Yahoo platform.  On 11/21/25 I went through the migration steps as instructed, but when I opened the email account, all of my email for the dates 11/15/25 to 11/20/25 disappeared.  I am hoping to retrieve the emails because there are important ones in there. Can anyone help me retrieve those email messages?