depressed

What are the signs and symptoms of someone who is depressed or who is facing the treat of going into depression???!!!! Lately, i find that i haven't been ME...!! I feel that i have lost a part of me, the jovial, happy go lucky , couldn't care a damn about trivial matter girl. i have lost interest in things that i used to love and enjoy, ie cooking, watching movies hanging out with friends..i used to excell in my studies, but now i find it hard to focus and concentrate...i brokedown more then twice this week for unknown reasons and i was never the kind who would tear up easily, however sad or piss i am.!!!! Shouldn't turning 20 be part of the happiest moments of my life..?? shouldn't studying overseas give me a whole new opportunity to explore a whole new culture, meet new ppl, do cool stuff?? Why is it that lately i have been feeling so down and keeping to myself..?? No ones knows that i have innner turmoil boiling up in my soul.. as most of the time i try really hard, try my best to put on a smile. Yet, i know, all this is just a mask i put on, to not unveil my inner thoughts and feelings. Only one close friend notice the change in me.. yet i try to avoid the topic. It is nice to know that i still have freinds who are concerned, but the truth is i dun think they are of much help in solving my problem. I have to dig down, go to the roots of all my problems and save myself from this terible situaions. That is easliy said then done. Anyway, i think this blog is a means for me to pour out my thoughts and feelings , to lift the big boulder that is burdening me and i really hope it does..so if anyone out there who is experiencing what i am now, i really do hope u guys could give me a word of advice as i really do not know what to do.. I know that my state of depression is just a minor one, but if i do not find the solution fast, i am quite sure that it will have a very strong negative impact on me later on...