Can you not access your website because of a theme error?
It recently happened to me. I navigated away from the WordPress admin area in the middle of a theme update and caused a huge error.
When I went to log in all I saw was a big error page. I first thought my IP address may have been locked out of my host, checked, nope.
Then I realized I caused the problem. I checked inside my Cpanel and noticed I had updated my theme but it was missing a stylesheet. I knew it would be fixed immediately if I changed the theme from Cpanel it would be fixed immediately. Here is how to do it.
Step 1 - Access Cpanel
If you are hosting with us you can access this from your administrator login area or just type it into the address bar. If your domain name was yourdomain.com it would be yourdomain.com/cpanel.
Step 2 - Go to PHPmyadmin
Again if you are hosting with us type in php in the search bar and click the application.
Once in phpmyadmin you will see your databases on the left. Click the one with your wordpress installation. Often times it will have WP and them a couple numbers like in this image:
Once you click the database there will be a drop down menu. select the wp options folder.
Next there may be a couple pages of results, go through them until you find a 2 files labeled "Template" and "Stylesheet" Next to those two items you should see the current theme. In the image below I have the Divi theme installed.
You will next need to click edit and type in the name of another theme that is installed on you wordpress site. If you recently started the site there is likely the "Twentyseventeen" theme. Next click "Go" in the botton right corner.
You will need to do this for both the Template and Stylesheet folders.
After that go to log in to your site as normal, is should be back and ready to go for you. I would recommend deleting and reinstalling the previous theme that broke.
If this doesn't fix the problem and you host with us, please submit a support ticket and we will see what we can do for you.