I have buy second hand iphone but owner also not remember apple id or password my phone show activation lock after reset so what can i do . Please help me

Hello~ Have the owner follow the information in the article I am posting. Click on below…

What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support

If they have the original receipt with the correct information, it may possible to go into Apple and have it reset. Barring the information above there is no other way to unlock the iPhone and it is useless to you. Read the user tip by *lobsterghost1* below…

The All Too Common SAD Reality of Buying a Used iPad/iPhone

~Katana-San~

There is nothing you can do! That phone will remain useless unless the previous owner remembers their credentials. Return it for your money back!

Return the phone for a refund.