I've read several posts about people having problems logging in WP. I've read several fixes as well, like
rename plugins folder, add new plugins folder, login to WP, delete the new plugins folder and change the name of the renamed plugins folder to its original (w/c is 'plugins)
which surprisingly works for many.
It didn't work for me though.
I found out that the problem occurred when I used a Cloudflare nameserver. So to others who have the same problem, you might think of this as an effective solution.
After using a cloudflare nameserver (to speed my site up) I wasn't able to login to WP. It redirected to a new URL, but still the login page-- no errors or anything. Literally nothing happens.
I noticed that this might not be a WP problem because the same thing happens with my Vanilla Forums, after receiving complaints from my site members. I tried to do the "rename plugins directory" remedy I've mentioned above. It didn't work for me. I knew this because I'm using a Custom WP Login plugin for my login page but even when I have renamed the plugins folder it should have been turned off. But it's still ON, even after I deleted cookies and used another browser.
This only means one thing. Cloudflare used a cached version of my site, a static version that can be used to speed up my site.
MY FIX: Turn Cloudflare off. Return to original nameserver settings.