执行sudo apt-get update报错且软件更新器、GNOME终端无法打开的问题求助

大家好，我现在碰到了个头疼的问题，想向社区的各位大佬求助：

当我在终端执行sudo apt-get update命令时，出现了如下报错输出：

Get:1 http://security.ubuntu.com/ubuntu kinetic-security InRelease [109 kB]
Hit:2 http://in.archive.ubuntu.com/ubuntu kinetic InRelease
Hit:3 http://in.archive.ubuntu.com/ubuntu kinetic-updates InRelease
Get:4 http://in.archive.ubuntu.com/ubuntu kinetic-backports InRelease [99.9 kB]
Ign:5 https://ppa.launchpadcontent.net/deadsnakes/ppa/ubuntu kinetic InRelease
Err:6 https://ppa.launchpadcontent.net/deadsnakes/ppa/ubuntu kinetic Release
404 Not Found [IP: 2620:2d:4000:1::3e 443]
Traceback (most recent call last):
File "/usr/lib/cnf-update-db", line 3, in
import apt_pkg
ModuleNotFoundError: No module named 'apt_pkg'
Reading package lists... Done
E: The repository 'https://ppa.launchpadcontent.net/deadsnakes/ppa/ubuntu kinetic Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: Problem executing scripts APT::Update::Post-Invoke-Success 'if /usr/bin/test -w /var/lib/command-not-found/ -a -e /usr/lib/cnf-update-db; then /usr/lib/cnf-update-db > /dev/null; fi'

除此之外，我的系统里软件更新器（Software Updater）和GNOME终端现在都打不开了，试了好几种办法都没解决，希望有经验的朋友能给我一些解决思路，万分感谢！

备注：内容来源于stack exchange，提问作者Sourav Shome