I can't log in with Facebook

Hello, I’m a Korean middle school student. I’ve used this program for 2 years, but recently, i can’t log in with this program. In the past, i signed in with my facebook ID, but there’s a problem to log in this program.  I want to recover it, but i can’t find a solution. Here is the message that I got.

There was a problem authenticating you with Facebook, sorry.
You may try signing up or log in with your username and password.
If you don’t remember your Prezi.com password you can create a new one.
In case you think the problem is on our side don’t hesitate to request for help on our support channels.

hi vera
same problem here…but a little bit different…downloaded prezi viewer on my ipad recently but I was never able to open it anyway.I did not even get a chance to register or create a password. Bad omen to start a new app,I guess :wink: when I try to log in with facebook or google, there is always this message „sorry there is a problem,please try again“ I tried every login option a several times and deleted the app and installed it again.I wanted to create a new password and Im still waiting for this email to reset it…I cant find it anywhere…not even in my spam folder.