Thanks @abletec
The issue was solved today, but had nothing to do with WordPress or plugins or any of that kind of things.
I moved a couple of weeks ago, and this was the first time I was trying to log in from my new house. Seems like the hosting provider had some sort of security measure, so when they detected a connection attempt from an IP address never used before, they blocked access from my IP. (at least that is whay they explained)
Everything is up and running now
Thanks anyway!
