I save my private key and save 10% lgx reward But now for login v2 ap There need 12 words nememoic What I do admin ?

you can claim in v2 of the app which is now live on the play store, App Store coming shortly. Please read this medium article fully which explains everything https://legionnetwork.medium.com/legion-super-app-v2-launches-be4bea482a27

Import your private key in tokenpocket then copy mnemonics their and Done ✅

First you create a new wallet, then import your old wallet with private key