How to changing display of samsung a30

Hi Magesh,

Sorry to say that iFixit doesn't yet have a guide for your phone, but fortunately they're not the only site dedicated to do-it-yourself repairs. There's a French site called SOSav that has a selection of repair guides, and luckily they have one for your phone.

Full screen (screen + frame) Galaxy a30 repair - Free guide - SOSav

The bad news is your phone is one of those where the screen is connected to a frame that holds basically everything else in the phone. So a screen replacement is going to mean gutting the phone; removing every single component inside it and moving them to a new screen/frame assembly. Anyone with a late model iPhone who's had to replace the back cover knows your pain.