Look at the source code of the page (right-click on the page and select View Page Source). You will see something like this:
<p>14 Bluefish Editor</p>
<li><p>VLC Media Player</p>
Notice that you messed up the listing after item 13. Edit the post and you will see that you used a different list marker after 13.
If you want an ordered list, just put any number before each item and Markdown will take care of the rest. If you want a bulleted list, use a + (plus), - (minus) or ***** (asterisk) sign.