@Wassim, Thank you. I can now enter the page builder. I do not recall deleting the index page. I had to put a maintenance page up and I made that the homepage. At another day I switched it back to the original by selecting the option "set as homepage". At another day I reverted to the maintenance page with the same option and it went live. I took a moment to change the name of what used to be the home page from HOME to home and that is when the builder took me out when I tried to save the changes. There is no way of deleting the index page because once it is set as a homepage the option to delete or rename the index page is not available. So, what happened? I surely didn't delete the index page. Another reason for knowing that is that the maintenance page was always running as the main indexed page so how would it be possible? Something else I noticed is that there were 2 index pages in the created in the code editor (index and index-1) I never named any of the pages as "index".
Could we have a dedicated option to make the website display an under construction and a maintenance page instead of creating a page to set as home page?