Many contacts lost

Hi, many of my contacts, but not all, disappeared some days ago (maybe 4 or 5). 

This is an old hotmail account, and I use it to store my phone contacts (synced with my phone). Now I get whatsapp messages from people that before where in my phone contacts and now they don't are. I checked my contacts on windows live mail but the newer ones (3 years or so) doesn't appear, and if I filter contacts by recently added, there are a lot of contacts added today, yesterday and so, but I have not added contacts this days.

Thanks for any help.