Contacts Lost From Microsoft Account

The contacts were there yesterday, but today only my Facebook contacts are displayed, not telephone and e-mail addresses from my Microsoft Account.

I logged into outlook.com to check the contacts online and the People page states that I have no contacts stored.

I cannot think of any action which would have caused this from my side, I haven't attempted to delete any contacts manually, and my phone appears to be connected to my Microsoft account correctly, but no contacts are there.

Please can you provide any possible reasoning as to why my contacts have disappeared from my Microsoft account and possible solutions to restore them?

Thanks,

Andy.