If you are a book or film lover, is there any subject or topic that you think any author/writer/producer/director has not written or shown yet?

All topics boil down to the same basic themes, and these have been covered by storytellers of all genres throughout time.
Conflict, love, overcoming adversity are popular themes that crop up in throughout history and across all creative media.
Storytellers can rehash these themes and the way that they represent them might be considered to be new or unique (for example, take James Cameron's 'Avatar', which is basically a rehashing of 'Pocahontas') but essentially, we relive the same stories over and over.
That doesn't mean we can't fall in love with them again and again, though!

I have never come across a movie on female infanticide, which although abolished, still prevails in many parts of the world!

Hard to bare stories about the realities of certain societies,  that people usually try to ignore. It mostly depends on the society and country, as some have done so and it pushed their country to do better in some way or other. However there are several societies or communities out there that are living in a caccoon of denial, and need to face the reality of their situation to get out of it.

In terms of lighter topics... there aren't many themes left, just different interpretations or versions.  It's all about the style and delivery after that.

based on true to life story

Of course, but that will have to be a very specific and recently brought up topic, like repercussions of the Arab spring on Muslim fundamentalist for example.

I want to read or watch something which the main plot or story line is based on psychotic fantasy.

We can't confirm that there is no subject or plot has been shown or written , it all depends on developing stories on life where we get all shows subject's