MySQL Service is not responding

A few days ago I notice that mysql service is not working, I have tried to restart it, but nothing, it sends an error like:

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

but ‘/var/run/mysqld/mysqld.sock’ does not exists.

I also tried:

$ sudo systemctl status mysql.service
● mysql.service - MySQL Community Server
     Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)
     Active: failed (Result: exit-code) since Fri 2021-04-09 15:02:51 EDT; 14s ago
    Process: 3222 ExecStartPre=/usr/share/mysql/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
    Process: 3230 ExecStart=/usr/sbin/mysqld (code=exited, status=2)
   Main PID: 3230 (code=exited, status=2)
     Status: "Server startup in progress"

Apr 09 15:02:51 ubuntu-s-1vcpu-1gb-sfo2-01 systemd[1]: mysql.service: Main process exited, code=exited, status=2/INVALIDARGUMENT
Apr 09 15:02:51 ubuntu-s-1vcpu-1gb-sfo2-01 systemd[1]: mysql.service: Failed with result 'exit-code'.
Apr 09 15:02:51 ubuntu-s-1vcpu-1gb-sfo2-01 systemd[1]: Failed to start MySQL Community Server.
Apr 09 15:02:51 ubuntu-s-1vcpu-1gb-sfo2-01 systemd[1]: mysql.service: Scheduled restart job, restart counter is at 5.
Apr 09 15:02:51 ubuntu-s-1vcpu-1gb-sfo2-01 systemd[1]: Stopped MySQL Community Server.
Apr 09 15:02:51 ubuntu-s-1vcpu-1gb-sfo2-01 systemd[1]: mysql.service: Start request repeated too quickly.
Apr 09 15:02:51 ubuntu-s-1vcpu-1gb-sfo2-01 systemd[1]: mysql.service: Failed with result 'exit-code'.
Apr 09 15:02:51 ubuntu-s-1vcpu-1gb-sfo2-01 systemd[1]: Failed to start MySQL Community Server.

Another thing is that now I have very big files in my data bases, and my disk is 100% full:

$ sudo find / -type f -size +1024M -exec ls -lh {} \;
-rw-r----- 1 mysql mysql 12G Apr  6 16:58 /var/lib/mysql/project_1/wp_options.ibd
-rw-r----- 1 mysql mysql 3.9G Apr  6 15:24 /var/lib/mysql/project_2/wp_options.ibd

I’am new to all of this about systems services and administration, so I don’t know whish steeps follows. I also tried this, but did not work either.

To finish, in /var/log/journal/11a47f9aabdc4fb2bec8c733d6ab3300/ there are files 50M+ of size, can I just delete’em?

Thanks a lot in advance.