They'll be out of circulation. Maybe you could try to brute force your way into them, but it's unlikely the lost coins will see the light of day with Bitcoin's security. Either way, it's one of the cons of decentralization.

no one can destroy bitcoin...because it is safe and well developed currency.

people should use bitcoins because it is secured currency...fast transaction and easy use of it..

if someone don't like bitcoin we can encourage them and convince them...that bitcoin is a better currency from all over the world.

bitcoin will survive like past some years...when peoples know about it...they will invest more in bitcoin.

nothing will happen to bitcoin...because it is decentralized currency..