EvilZone

I am new to evilzone and also new to programming world.I don't know what to write but still wanted to ask/write something here and I want to say thanks to managing community of this awesome forum.
I want to ask a question which I think no one can answer better than you people
"Can I replace/modify the operating software of mobile phone or other such devices by reprogramming it or anything like that" if it is possible then tell how can I do it.
                                                                                                          Thank you..
                                                                                                            Meer