A week or so back Blogger went seriously wrong, most of us probably noticed! For me it came back for a couple of days but has been unreliable ever since, up and down like a fiddler's elbow, as they say in polite circles. It's been permanently unavailable now for 2 days.
I could read Blogger blogs but couldn't log into my own or add any comments to others - all I got was a login screen that just recycled back so I couldn't even be anonymous.
Having cleaned cookies, reset histories and the like to no avail I tried Internet Explorer, and bizarely it seems to work under IE. Someone else commented on the Blogger help site that they could only make it work under Opera or on an Android phone. Something is presumably being mis-cached or has been messed up in the browser (if so what were Google doing to the browser?).
So I'm just just passing along the tip, if Blogger fails again for you try a different browser.