Lost access to /wp-admin/...

I have blocked access to my webpage as a simple way to restrict access while I am setting up the website. I have done this by blocking all IP addresses except my own in WPMU Defeneder.
I know, it looks preety stupid now...
Then I was updating some plugins earlier today. The first one failed and my access to anything below /wp-admin/ was lost.
I can see the frontend but cannot login to backend.
Will it be better when webserver restarts? It is done automatically every 6 hours.
Can I help myself through FTP access?
Thank you.