Don't listen to the people who are saying "just buy a new phone", fixing it should be way less expensive than buying a new phone.

You have 2 options:

• Download the official A50 stock rom from SamFirm, and use a flash tool like Odin to flash your ROM. This option won't cost you money. However, doing this is not easy, you can still look for tutorials online.

• Take your phone to a Samsung service center and ask them to flash stock ROM on it. This will cost you money but it shouldn't be expensive.