My contact list is all of a sudden showing contacts from another user;  mine just disappeared. I need them back!

I noticed that the contacts from my contact list do show in the "To" dialog box that comes up when I want to select mail recipients. How do I get my contact list back? They always used to be the same ones that show in the "To" dialog box but they have been replaced by someone else's.

[I only use this client and gmail.]

Joe