If you followed each step of the tutorial, including the one which backed up your crontab file, you can restore it with:
sudo cp /etc/crontab.bak /etc/crontab
Otherwise, you might try repairing yours by looking at the screenshot in the article, or pasting this in:
#minute hour mday month wday who command
#*/5 * * * * root /usr/libexec/atrun
# Run daily/weekly/monthly jobs.
15 3 * * * root periodic daily
30 4 * * 6 root periodic weekly
30 5 1 * * root periodic monthly
Hope that helps...