I lost the original files of a scorm created on Captivate and want to actualize it

There is no way to create a raw cptx-file from SWF or HTML output. Since you talk about 'SCORM' packages, which means that you need interactive output, the possibility to record the SWF file while playing (that is pretty easy) is not a solution neither, because you'll end up with a passie video. You could add some interactivity to result in an interactive video, but never will you be able to convert to a SCO. Interactive video only supports Knowledge Check slides, which cannot be reported.

More in:

http://blog.lilybiri.com/using-cpquizinfoanswerchoice-for-survey-conversion-from-swf-to-html

I'm afraid that once you publish a course there is no way you can simply convert it pack to a source file that can be further edited or republished using Adobe Captivate. I'm assuming the original is published as an SWF because you say "convert them into html5." If you can get a Flash player or a third party tool that will play the flash content you could capture it as a movie and import it into Captivate. You might also be able to record it as software simulation to get the content into a new Captivate project but it's doubtful you can find a player that will play Flash based content at this late date.