How do I help my friend with psychological issues

Okay my friend has a really self-destructive personality and before I just figured that she was the ‘attention wh*re’ until recently I found out that she over-dosed on pain-killers and now she has gone missing - we can’t find her anywhere.

I’ve come to the conclusion that she has inlaying psychological issues except I don’t know how to identify exactly what they are, or how to help her.

Firstly, Anne is 18 - she parties, drinks, possibly has/still does drugs and she has sex [I dunno if she’s currently active right now in the just mentioned]

Basically, she always tells lies about everything - almost compulsively she has to lie, whether it’s about her having her own place or her own car, cutting herself, doing drugs, or even small things like how she can download from youtube and I told her I tried it and she sort of ‘lags’ at being caught out.

She supposedly had an abortion recently - but we’re not sure, because we can rarely tell if she’s honest or not and we just can’t understand why she has to lie about every little thing and just keep on making up bs stories.

And she is just so unstable sometimes - one minute she’s happy and she’s your best friend, next she doesn’t bother with you, or she’s depro… It’s hard to explain her behavior…

Anyway, the point is - she needs attention and… urgh, I honestly don’t know what to do or how to help her. Is there a way I can classify her personality/psychological issues…??

I mean I know I haven’t made it clear here - but it is obvious to me she has issues… whether she’s bipolar or something… heeelp!!!