Please edit your
/etc/apt/sources.list , remove the contents from it and include just the below lines.
deb http://deb.debian.org/debian buster main contrib non-free deb http://deb.debian.org/debian buster-updates main contrib non-free deb http://security.debian.org/buster-security/ buster/updates main deb http://ftp.debian.org/debian buster-backports main contrib non-free
Note that this use case covers almost every safe way of installing packages in Debian.
- non-free is needed for proprietary drivers
- backports are for fresh new stuff which might not be covered or old
- buster-updates covers new updates for buster
- Don’t forget to do an
apt-get updateafter changing the file.