References is not showing up - Bibtex

Before getting to the heart of your question, let me point out that the BibTeX source data you've obtained -- presumably from some online repository -- is a curious mixture of what would be appropriate for an entry of type @article on the one hand and an entry of type @misc on the other. To wit, if one goes to https://arxiv.org/abs/0905.0695 and clicks on the "Export citation" link on the right-hand side of the window, one can choose between two entirely different citation data formats. One is the published journal article form, viz.,

@article{Riess_2009,
   title={A REDETERMINATION OF THE HUBBLE CONSTANT WITH THE HUBBLE SPACE TELESCOPE FROM A DIFFERENTIAL DISTANCE LADDER},
   volume={699},
   ISSN={1538-4357},
   url={http://dx.doi.org/10.1088/0004-637X/699/1/539},
   DOI={10.1088/0004-637x/699/1/539},
   number={1},
   journal={The Astrophysical Journal},
   publisher={IOP Publishing},
   author={Riess, Adam G. and Macri, Lucas and Casertano, Stefano and Sosey, Megan and Lampeitl, Hubert and Ferguson, Henry C. and Filippenko, Alexei V. and Jha, Saurabh W. and Li, Weidong and Chornock, Ryan and Sarkar, Devdeep},
   year={2009},
   month={Jun},
   pages={539–563}
}

The other is the Arxiv eprint form, viz.,

@misc{riess2009redetermination,
    title={A Redetermination of the Hubble Constant with the Hubble Space Telescope from a Differential Distance Ladder},
    author={Adam G. Riess and Lucas Macri and Stefano Casertano and Megan Sosey and Hubert Lampeitl and Henry C. Ferguson and Alexei V. Filippenko and Saurabh W. Jha and Weidong Li and Ryan Chornock and Devdeep Sarkar},
    year={2009},
    eprint={0905.0695},
    archivePrefix={arXiv},
    primaryClass={astro-ph.CO}
}

I believe you should choose one or the other publication format -- but not a hybrid of the two.

Let's stick with the @article version but also (a) fix the odd-ball uppercasing of the title field and (b) truncate the list of authors as per what you showed in your posting:

@article{Riess_2009,
    title={{A Redetermination of the Hubble Constant with the 
       Hubble Space Telescope from a Differential Distance Ladder}},
   volume={699},
   ISSN={1538-4357},
   url={http://dx.doi.org/10.1088/0004-637X/699/1/539},
   DOI={10.1088/0004-637x/699/1/539},
   number={1},
   journal={The Astrophysical Journal},
   publisher={IOP Publishing},
   author={Riess, Adam G. and others},
   year={2009},
   month={Jun},
   pages={539-563}
}

Observe that this entry features fields named doi, url, and issn.

Aside: It's important to be aware of the fact that the unsrt bibliography style has been around in essentially unchanged form since the mid-1980s [!]. Back then, the Internet was but a gleam in the eye of Tim Berners-Lee, and nobody had yet conceived the idea of storing publications in electronic form at (electronic) locations identified by their URLs. Maybe unsurprisingly, then, the unsrt bibliography style has not been programmed to recognonize fields such as doi and url; unrecognized fields are simply ignored.

What to do, then? I suggest you switch from using the cite citation management package and the unsrt bibliography style to the natbib citation management package and the unsrtnat bibliography style. You should also load the url (or, better yet, the xurl) package -- as well as the hyperref package if you want the URL strings to be clickable hyperlinks.

Observe that the contents of the issn, doi, and url fields are all shown. That's presumably way too much information; you might decide to delete the issn and doi fields.

documentclass[12pt,a4paper,titlepage]{article}
usepackage[a4paper, total={6.5in, 8.5in}]{geometry} 

begin{filecontents}[overwrite]{References.bib}
@article{Riess_2009,
    title={{A Redetermination of the Hubble Constant with the 
       Hubble Space Telescope from a Differential Distance Ladder}},
   volume={699},
   ISSN={1538-4357},
   url={http://dx.doi.org/10.1088/0004-637X/699/1/539},
   DOI={10.1088/0004-637x/699/1/539},
   number={1},
   journal={The Astrophysical Journal},
   publisher={IOP Publishing},
   author={Riess, Adam G. and others},
   year={2009},
   month={Jun},
   pages={539-563}
}
end{filecontents}

usepackage[numbers]{natbib}
bibliographystyle{unsrtnat}

usepackage{xurl}
usepackage[colorlinks,allcolors=blue]{hyperref}

begin{document}
cite{Riess_2009}
bibliography{References}
end{document}