Hello,
We are really sorry for the inconvenience.
Please follow below steps to restore deleted contacts.
Login to people.live.com and sign in with effected email address and password.
then towards top of the screen click on " Manage" and then click on " restore deleted contacts.
This should recover all deleted contacts.
Note: If its a free hotmail account then there is possible your email account had migrated to exchange server, which is happening to all Microsoft account across of the world and this will take some time to get back all the information saved on your account.
Thanks
Jason