Two more things to consider. 

1. Make sure your BibTeX file is in the same folder as your main LaTeX file. The BibTeX file will be a text file with a .bib extension.

2. BibTeX doesn't like spaces in the path to the bib file. This usually only a problem if your bib file is not in the same folder as your LaTeX file. 

Finally, some LaTeX editors need you to run BibTeX before you compile the document. 

Hi,

Thanks Michael and Logan for your inputs. 

Can you please send me the template files (working) if you have for journal of computational physics. 

I downloaded the enum.sty file and the error is gone but the template file have few pre-compiled pdf files and my pdf does not look anything like them. 

I am sorry for sounding naive

By template do you mean document class?  If so, in LyX you can select the Elsevier document class by slecting Document -> Settings. Look for Elsevier Article. You might also look at the attached link.

http://wiki.lyx.org/Examples/Elsevier

Could you please send a copy of the template, I could not find it from Journal of Computational Physics website.

Thanks

Hi Shashank and Hayder, 

  I checked the Journal of Computational Physics site and in their "Guide for Authors" page (first link) they direct to another "LaTeX instructions" page (second link). I downloaded the "sample manuscript"(third link) and compiled myself (attached) to see any issues. It compiled like charm without any issues. 

If you find any other issues, let us know. Hope this helps. 

https://www.elsevier.com/journals/journal-of-computational-physics/0021-9991/guide-for-authors

https://www.elsevier.com/authors/author-schemas/latex-instructions

https://www.elsevier.com/__data/assets/file/0007/56842/elsarticle-template.zip

Thanks Ranga

Appreciation!