Why have my contacts and email disappeared after upgrading to Win10?

[Windows Central Question]

why my contacts and email has disappeared after upgrading to win10

there are no contacts in my phone although when i go to social apps like whatsapp,viber,line etc they have my contact added
and one more thing i cannot add my hotmail account to my lumia 535 , it adds my yahoo mail ,my gmail but is not adding my hotmail.but i cn download apps from win store...