Unfortunately isn't GetSimple working well anymore.

[Connie]

1)
it would be helpful if you do the health check in "settings / first steps / health check" and tell us the results

2)
does this happen as well when you deactivate the friendly urls?

3)
did your hoster change the environment, maybe changed the PHP-version or something similar?

all these are just questions as you forgot to send the attachments

cheers, Connie

bytheway, there are quite some postings here with "can't login" etc. Did you run a search for them, did you check the suggestions there?