Not a happy topic but I have just been reading the very sad twitter posts sent by Molly Russell to various celebrities. She was the teenager who later went on to take her own life. So often it’s extremely difficult for parents to know what to say and do if their children are depressed. This guide seems very helpful.
https://www.youngminds.org.uk/parent/parents-a-z-mental-health-guide/suicidal-thoughts/