I have a new computer and i cannot retrieve my itunes library

What happens ? The purchases that you can redownload will show in the Purchased link under Quick Links on the right-hand side of the iTunes store homepage, or on the current version of iTunes click on your name/icon towards the top right of iTunes and then click Purchased on the popup :

For items no longer in the store and your own content either copy them from your backup of old computer's iTunes library into your new computer's library via File > Add To Library, or if you still have your old computer with them on : How to move your iTunes library to a new computer - Apple Support

Re-downloading purchases does not restore your library. You will be missing all your playlists, ratings, play counts, date added, as well as any modifications you made to tags/labels. It also won't re-download items you have from other sources such as CDs (unless you subscribed to iTunes Match, and even then they may not be identical to your originals). It is not good to rely upon the Store always having purchases available for re-download as Apple cannot guarantee they will always be there. Instead copy your library from your old computer or the backup you make of it because you know one day somebody will steal it, or there will be a fire, or a spilled cup of coffee...

Moving a library: Quick answer if you use iTunes' default preferences settings: Copy the entire iTunes folder (and in doing so all its sub-folders and files) intact to the other drive. Hold down the option (alt) key (shift on Windows) and open iTunes. At the select prompt choose the iTunes Library.itl file in the copied iTunes folder.

I have not used my itune account since 2013 and I never owned a iphone so how do I retrieve my music

Retrieve from where ? For music purchased from iTunes, and which is still in the store, not bought from a different country's store, and which you haven't hidden from the cloud, what you can redownload will show in the Purchased section : Download your past purchases - Apple Support