restart apache service automatically using cron 12AM daily

I got it and give you step by step adding cron jobs into your system:

1. Login to your server with SSH
2. Type crontab -l to display list of cron jobs,
3. Type crontab -e to edit your crontab,
4. Add 0 4 * * * /etc/init.d/mysqld restart to restart Mysql everyday at 4 AM,
5. Add 0 5 * * * /etc/init.d/httpd restart to restart Apache everyday at 5 AM and
6. Add 0 24 * * * /etc/init.d/httpd restart to restart Apache everyday at 12 AM
7. Save your file,
8. Recheck with crontab -l

While @einterview's answer is almost correct, it's important to note that a * in the minute column will run the job every minute of that hour. If intending to run once every hour, steps would be:

1. SSH into server.

2. Get list of current user's jobs with $ crontab -l

3. Edit jobs list with $ crontab -e (default editor will open)

4. Add 0 4 * * * service mysql restart for mysql at 4:00am

5. Add 0 5 * * * service apache2 restart for apache2 at 5:00am

6. Add 0 0 * * * service apache2 restart for apache2 at 12:00 am

7. Save and close (Ctrl+O and Ctrl+X in nano)

8. Recheck with $ crontab -l