Use the adjective troubled to describe someone who is upset or distressed, or a situation that is difficult. If your mom and your sister fight a lot, often bitterly, you might say that their relationship is troubled.
A troubled neighborhood might be one that faces problems like poverty and crime. If you are troubled, however, you might simply be worried — and the troubled expression on your face might be enough to make your friends ask you what's wrong. The figurative phrase "troubled waters" means a particularly tough period or situation: "I'll stick with you through troubled waters!"