I tried to disabe all the third party modules and nothing. I don't know why I can not acces to my backoffice but I guess It's because my web is infected. I have contacted a company that says they can solve the problem(I hope so), if they do I will share how do they do it.
Btw, when I changed my hosting, I went from http to https (about a month ago), but it was this week when I was unable to acces Backoffice.