1、查看此路径下有没有对应的mysql.service文件，有且只能有一个对应的文件名称

ps: 我这里面有两个是因为之前换过mysql的版本，可能没有删除干净导致重启MySQL服务不好使。如果你有两个以上的话，保留最新的

2、如果没有mysql.service。在第一步的路径下面添加一个，有且只有一个。

# Copyright (c) 2016, 2023, Oracle and/or its affiliates.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License, version 2.0,
# as published by the Free Software Foundation.
#
# This program is also distributed with certain software (including
# but not limited to OpenSSL) that is licensed under separate terms,
# as designated in a particular file or component or in included license
# documentation.  The authors of MySQL hereby grant you an additional
# permission to link the program and your derivative works with the
# separately licensed software that they have included with MySQL.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License, version 2.0, for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
#
# systemd service file for MySQL forking server
#
[Unit]
Description=MySQL Server
Documentation=man:mysqld(8)
Documentation=http://dev.mysql.com/doc/refman/en/using-systemd.html
After=network-online.target
Wants=network-online.target
After=syslog.target
[Install]
WantedBy=multi-user.target
[Service]
User=mysql
Group=mysql
Type=notify
# Disable service start and stop timeout logic of systemd for mysqld service.
TimeoutSec=0
# Execute pre and post scripts as root
PermissionsStartOnly=true
# Needed to create system tables
ExecStartPre=/usr/bin/mysqld_pre_systemd %I
# Start main service
ExecStart=/usr/sbin/mysqld --defaults-group-suffix=@%I $MYSQLD_OPTS
# Use this to switch malloc implementation
EnvironmentFile=-/etc/sysconfig/mysql
# Sets open_files_limit
LimitNOFILE = 10000
Restart=on-failure
RestartPreventExitStatus=1
# Set enviroment variable MYSQLD_PARENT_PID. This is required for restart.
Environment=MYSQLD_PARENT_PID=1
PrivateTmp=false

3、再次尝试重启MySQL服务命令

systemctl restart mysqld.service