Sorry for delayed response, yes I am pretty sure it is the ThemeMyLogin that was the issue – google and you will see many with the same problem or check out these posts https://www.ads-software.com/support/topic/too-many-redirect-loops?replies=29
Basically, the minor bugs in how it works are liveable if you have no other option, but if once you’ve installed it you decide you would like to deactivate or remove it ThemeMyLogin becomes a bit of a cancer bomb. It doesn’t have a clean uninstall, so even after deleting everything you can your website’s login still won’t work..
Yes my site had been backed up and luckily was in testing mode rather than with live customers. In the end I had to back up to a week prior to de-activating TML – because it is the deactivation that causes the biggest headache.
So I am stuck with TML because to remove it is to totally screw my website! Wish I had never installed it. Can’t go back now.