+ Deactivating your account will disable your profile and personal stuff like (messages, photos, friends etc..) but won't disable your public data like (blog, posts, group topics etc..)
+ You can deactivate your account from account settings page under My Stuff menu
+ You can re-activate your account again anytime you want.
just login with your username
and password normally and
select activate link, all your private information and friend
list will be restored.