Could be nothing, just an overly busy mind and an introvert, or could be the beginning stages of schizophrenia. Her talking to herself and constant hand running coul be her way of trying to stay focused and not get lost in her mind that could be unraveling. Your best bet is to get her to a skilled and educated professional to talk to her and see if they can help. It's unlikely judging by your comment that she will talk to you about it, or even admit it, possibly not even to a professional for several sessions.
Losing your mind is quite possibly the most frightening thing an intelligent person can ever go through, be sensitive about it.
[–] 7681120? 0 points 1 point 1 point (+1|-0) ago
Could be absolutely nothing, especially depending on age. Is she lonely? Is she depressed? Is she thinking? Is she bored? I'm sure we all do strange things when we think we're alone, we just don't find them strange but others probably would. Sometimes they are nervous ticks. Sometimes they are done on purpose just to have something to do.
It definitely could be something and it definitely could be nothing. The FIRST thing I would do is pay attention to what she is saying when she talks to herself? Is she thinking out loud? Is she having a conversation with herself? Is she having a conversation with someone not in the room. While I would probably have the same reaction as you if I were in your shoes, I can honestly say that it could legitimately be nothing at all. Be careful and compassionate either way. I'm not sure I'd address the situation unless something alarming starts happening like playing with knives are talking aloud about killing herself or dying.
[–] chuckletrousers 0 points 2 points 2 points (+2|-0) ago
Gently ask her what the problem is instead of trying to guess or ask strangers opinions.
[–] Neelqm [S] 1 point -1 points 0 points (+0|-1) ago
Thank you for your reply i tried to talk to her about this but she did not answer me clearly . But anyway i appreciate your response.
[–] chuckletrousers 0 points 1 point 1 point (+1|-0) ago
Sometimes it takes a good while for them to say what the problem is.