Thanks for reply but,
I've tried to install spotify the way you said and that worked (hopefully it won't disappear), but i still cannot install anything using snapd.
Listed commands to fix snapd did nothing and sudo apt install --reinstall zorin-os-desktop showed these errors:
dpkg: ubuntu-docs: dependency problems, but removing anyway as you requested:
gnome-user-docs depends on ubuntu-docs (>= 18.04.1~) | zorin-os-docs (>= 15.0); however:
Package ubuntu-docs is to be removed.
Package zorin-os-docs is not installed.
update-alternatives: error: alternative path /usr/share/gnome-shell/theme/zorin.css doesn't exist
dpkg: error processing package zorin-desktop-session (--configure):
installed zorin-desktop-session package post-installation script subprocess returned error exit status 2
Setting up rhythmbox-plugin-alternative-toolbar (0.18.0-1) ...
Setting up gnome-sushi (3.24.0-3) ...
Setting up zorin-appearance-layouts-shell-core (2.1.2) ...
Setting up totem (3.26.0-0ubuntu6.2) ...
Setting up libevolution (3.28.5-0ubuntu0.18.04.2) ...
Setting up totem-plugins (3.26.0-0ubuntu6.2) ...
Setting up zorin-connect (1.1.1) ...
Setting up brasero-cdrkit:amd64 (3.12.1-4ubuntu2) ...
Setting up brasero (3.12.1-4ubuntu2) ...
Setting up gnome-maps (3.28.1-1) ...
dpkg: dependency problems prevent configuration of zorin-os-desktop:
zorin-os-desktop depends on zorin-desktop-session; however:
Package zorin-desktop-session is not configured yet.
dpkg: error processing package zorin-os-desktop (--configure):
dependency problems - leaving unconfigured
Setting up libfolks-eds25:amd64 (0.11.4-1ubuntu1) ...
Setting up gnome-contacts (3.28.1-0ubuntu1) ...
Setting up evolution (3.28.5-0ubuntu0.18.04.2) ...
Setting up evolution-plugin-pstimport (3.28.5-0ubuntu0.18.04.2) ...
Setting up evolution-plugins (3.28.5-0ubuntu0.18.04.2) ...
Setting up evolution-ews (3.28.5-0ubuntu0.18.04.1) ...
Setting up evolution-plugin-bogofilter (3.28.5-0ubuntu0.18.04.2) ...
Processing triggers for libc-bin (2.28-0ubuntu1+zorin4) ...
Errors were encountered while processing:
zorin-desktop-session
zorin-os-desktop
E: Sub-process /usr/bin/dpkg returned an error code (1)
Also out of nowhere sudo apt update is now showing this error:
E: The repository 'http://ppa.launchpad.net/synapse-core/ppa/ubuntu bionic 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.