Some examples of threads which already exist about this:
Do we get our contacts back?
Connection Error
Will NOT sign in!
Live! Messenger .. lots of bugs??
Unable to load contact list
Cannot sign in and no error message?
I very strongly suggest to read them, they answer your question.
Yes you will get your contacts back as the list you see (or rather not see) is a cached list used as long as the connection can't be properly established, as explained in many threads about this....
Please do not make multiple threads about this (and in the wrong forums)
To others, if you see such duplicated threads, PLEASE do not continue them, rather link to the existing ones and REPORT the thread for closure (or even better and if possible to merge to the existing one).