When I try to log in at "example.com/wp-login.php" (which loads fine and is the way I always log in), I only get a "No data received" error in Chrome 26, a blank white page in Safari 6.0.3, a "Connection was reset" error in Firefox 19.0.2, and a "Connection closed by remote server" error in Opera 12.14. I can't get in to do anything! Everything was working fine yesterday and I did nothing (no updates or changes to files or anything) between then and now.
-Yes, my internet works. I can load other (non-cached) sites with no issue.
-I cleared my cache, reset browsers, reset computer, reset wifi, tried on another computer with a different operating system and a different ISP-- still no luck.
-I tried deleting cookies, checking that cookies were enabled-- still no luck.
-No, this problem is not limited to one wordpress site. I manage 10 (not multisite; they're separate). I'm getting the same errors on all. And no, not all 10 sites are on the same server, or even the same hosting provider.
-I tried to think of plugins that I might use on all sites that could be causing this, but there are none i can think of.
I don't know what else to check!! Please help. Thanks.