You can load new software although you need to have some know how on what to do. It’s a big ask to have someone explain step by step. You might be better off taking it to a repair store and seeing if they can flash it for you. But if you want to give it a go you need to
Download Odin (Flashing software)
Find your correct firmware for your device (Google)
Download said firmware
Put your phone into download mode (Volume down + Home button)
Connect your phone to your PC via Cable
Open Odin with phone connected and import firmware into AP
Make sure you have everything correct otherwise you run the risk of bricking your phone.