How can I find out whether a person is still alive/or at their previously known address.?

Question

she has been very ill for a very long time, and uncontactable for a month.

Answer 1

Hit http://people.yahoo.com and call them.

Answer 2

If you don't live close to her and can't just go over there then call the local police department and have someone go and check things out, if you are really worried...

Answer 3

plug the address into whitepages.com and see if her name is still registered at that address.