When someone losts his bitcoin wallet he/she lost his bitcoins and never possible to get it but where goes it? or Can anyone get it or be benefited like traditional currency?
Lost Bitcoins can not be retrieved. They will be forever lost. This, according to basic economical theories, will lead Bitcoin to increase its value over time (a.k.a. deflation).
The greatest thing about Bitcoin is that we all get to be our own bank. And the scariest thing about Bitcoin is that we all get to be our own bank.
I quote this. Being our own bank has many advantages, but it takes responsibilities as well. Keep in mind this, take care of your seeds, passwords, private keys and act just like you are a bank. Yes, a 'real' bank which should to have strong security measures to protect funds against thieves, incidents and loss.