Hi! I have a tip for you guys. If the issue is that all your contacs are gone from your contact list, i.e you can log in, but your contact list are empty, howerver, if you go to people.live.com you can see all your contacts read the following:
This issue should now be resolved in the latest relese of messenger.
Try to reinstall WLM with CleanUp Utility, download from:
install it and remove ALL WL components, not just messenger.
Go to download.live.com and reinstall Messenger and any other WL products you want. This should resolve the issue with the disappearing contact list
Hope this helps some1!