Abstract appeared in the abstract book of a conference but the paper is not published, can I publish it elsewhere? I intended to participate in a conference, I sent my abstract and it was accepted. For some reasons, I didn't go to that conference and I didn't send my final conference paper.

However, my abstract (title, authors, abstract, keywords) is shown in the published abstract book of the conference and can be easily found online.

My question, since I didn't publish that work, I want to publish that same work in a different conference now, can I use the same abstract? Or I have to change it.
Yes. In my field you don't publish the same but you can present more than twice. Because conferences aren't journals but are seen as moments of discussion and dissemination of ideas and results. 

I would avoid the same wording anyway. This gives idea of laziness at least if one is not sure to have found the perfect wording. 

It might be different in fields where conferences are seen as the major source for results, but still, up to date, your results are not in the wild and they just left a trace as simple abstract.