My childhood's best memory, where are you?

Sparrows were considered to be every home's bird back in 90s. We could easily see two or three just sitting on our balcony shelf. My favourite childhood memory was also seeing sparrows flying from one home to another but now in the 2000 era, we are hardly seeing any of our childhood bird around our house. What exactly are the reasons for the sparrows to vanish like that from Delhi?

With Delhi running fastly into modernisation and modifying itself into a modern urban living, there is no space for the bird that has always been a part of our household. Lack of ventilators, houses are now made up of glass panels leaves no room for sparrows to make their homes. There are no green trees in your yards now, most of us do not have yard at all as all we see is concrete building everywhere in Delhi. For the majority of children in Delhi, a sparrow is only a pretty picture in their bird books. Noise, installation of mobile towers, radiation have made these bird's life hell. Some have died already and some are on the verge of extinction. We as humans have exploited Delhi bird's  natural home and habitat. So, what can we do?  
You will get to know about interesting solutions that individually you can do to revive your childhood bird in your  house  again. So, stay tuned................