wp-admin stuck to a dummy page

Hey guys, how are you?

I am fairly new to WP and I have been struggling quite a bit. It’s easy, but I am quite dumb.

Well, what brings me here is that I actually messed up some configs. On Configurations > General, there’s an option to set up an URL for the site. I thought it would redirect my domain to a page I’d set up.

However it didn’t happen – I redirected it /splash.php, and now my wp-admin simply won’t open.

My site: iplugger.com.br

It also broke all the layout.

How can I get it back to where it was?

Thanks in advance