Where are My Sparrows gone?

Whenever I look at a sparrow (Passer domesticus) , it reminds me of my childhood as I grew up among the sparrows in my house. There were hundreds of them in my roof. But where are my sparrows now? I never realized the number of sparrows in my house was reducing slowly until now that I scarcely able to see any.
I see less number of sparrows every where now. What happened to them?

Being worried, I tried to find out the situation worldwide, and similar situation exist everywhere. May be there are animals who need more attention now but if we leave the situation of these house sparrows unattended now, it may lead to a future concern. I will request a mild effort from every person to save these small creatures, which are facing some problem without our noticing them.

While going deeper into the cause of this problem, I came across one reason which could be the reduced nesting place of these birds. As the old houses are renovated and older nest are being destroyed and newer houses doesn’t provide congenial place for building a nest.
So, Lets take a pledge, that whenever we come across any nest of sparrow, we shall try to protect them.
My Friends, Let Us Save Our Planet.