debian 10 apt - The repository does not have a Release file

solution

deb [trusted=yes]

see last line

# deb cdrom:[Debian GNU/Linux 10.4.0 _Buster_ - Official amd64 xfce-CD Binary-1 20200509-10:26]/ buster main 


deb http://security.debian.org/debian-security/ buster/updates main
deb-src http://security.debian.org/debian-security/ buster/updates main

# buster-updates, previously known as 'volatile'
# A network mirror was not selected during install.  The following entries
# are provided as examples, but you should amend them as appropriate
# for your mirror of choice.

deb http://deb.debian.org/debian/ buster  contrib main    
deb-src http://deb.debian.org/debian/ buster main contrib    

# This system was installed using small removable media
# (e.g. netinst, live or single CD). The matching "deb cdrom"
# entries were disabled at the end of the installation process.
# For information about how to configure apt package sources,
# see the sources.list(5) manual.

deb [trusted=yes] file:///home/ayush/OS/apt/debian_10_files/ buster contrib main
# deb-src [trusted=yes] file:///home/ayush/OS/apt/debian_10_files/ buster contrib main