You are setting up Solr cores, and it is getting disappeared on restart. Is this happening with you? Yes, It did happen to me as well when i got a chance to setup Solr for one of the Sitecore project.
I installed Solr 6.2 and completed all the installation and configuring steps. Than i started to create multiple cores for multiple indexes (Sitecore indexex like master/web/core/analytics etc.).