I know it is a very boring and low topic for conversation, but i just want to know how do you know i you are depressed/stressed?

The symptoms that the person in question has got are:
Crying all the time over silly things
Feeling extremley low
Not sleeping
Snappy
Mardy
Really bad headaches
Loss of appetite

anyone got any advice?

http://www.sheffieldforum.co.uk/showthread.php?t=47377&highlight=depression

Some good advice there.

I'd go to the docs, they will probably give the person concerned some exercises to do, or have regular sessions, drugs won't be the first option so no need to worry about that.

It sounds like the person concerned really needs too seek some sort of professional help though.