Can no longer access my site – help!

I was working on my new website in the wordpress dashboard. I was in Settings – General and I changed the wordpress site and the original site from https://www.rentheseries.com/wordpress to just https://www.rentheseries.com hoping it would mean my site could be viewed from just typing https://www.rentheseries.com. However it’s just crashed it now and I can’t get back into it to change it back. The https://www.rentheseries.com/wordpress/wp-admin doesn’t work, nor does https://www.rentheseries.com/wp-admin. How do I get access to my wordpress now? I can access my ftp but I don’t know what I need to do to it to fix the problem.

Please help!
Kate