Lost contacts and some just have the number with no detail

I have suddenly mysteriously lost a number of contacts from my iCloud contacts. Some of the contacts have disappeared completely, others that I have contacted in WhatsApp just show the number.

I have tried restoring it back to when I knew they were all there but it hasn't made any difference and I really need some of the numbers - any help would be much appreciated!

They have disappeared from all my devices and my iCloud account, so I assume its an iCloud issue. I don't use any other accounts.

Thank you in advance.