OK. I deactivated my plugins as above and was then able to access admin.
Then I changed theme (actually it was already changed somehow) to the default theme.
Then my site came up.
I went back and activated my theme.
So far so good.
Reactivated the plugins one by one. Tested the site after each one.
One of them seemed to make me blank again so I deleted that one from my plugins folder and I seem to be OK.
Whew.