lsblk should have contained info on filesystems - a response similar to
$ lsblk -fs
NAME FSTYPE FSVER LABEL UUID FSAVAIL FSUSE% MOUNTPOINTS
sda
└─sda1 ext4 1.0 a0a54066-5053-4aaf-b0de-0cf5fefeb260 184,7G 55% /a/virtualbox
sdb
└─sdb1 ext4 1.0 private 1f3d1a6e-b4b5-46da-909a-8a87a45dd18b 212G 41% /a/private
sdc
sdd
sde
nvme0n1
└─nvme0n1p1 ext4 1.0 projects 04f0ac14-1556-4666-9f12-617ba471502c 1,4T 13% /a/projects
nvme1n1
├─nvme1n1p1 vfat FAT32 AD24-B748 299M 0% /boot/efi
├─nvme1n1p2 ext4 1.0 cafce1fc-a404-48b9-b7e8-00ec59a4e2c0 570,2G 29% /
└─nvme1n1p3 swap 1 swap 3cd93eae-1d0d-4ce6-a7e6-7df665e8cede [SWAP]
The lack of info points to filesystem meltdown - the filesystem table has been wiped. This is often caused by powerspikes or flashes in the powerline - a rapid loss and return of power - like a fingersnap.
I hope you have a separate copy of important data, because restoring from this disaster will be difficult even for an expert and it cannot be done using forum support.
Your best way forward is to reinstall the operating system.
If you want to try rescuing data I suggest downloading and using an ISO with the necessary tools.
It will also require some external storage capable of holding the data recovered from the crashed system.
- https://www.system-rescue.org/ provides an Arch Based system with tools
- linux-aarhus archive @ uex.dk provides a Manjaro based system with tools
- Mace & MaceR - Manjaro cscs Edition & Recovery - KDE & LXQt+KWin