Free of charge file sharing site?

I've been looking for a file sharing site, free of charge, in Google. There are lots of pages listing file sharing sites, for instance, "Top ten file sharing sites". Unfortunately, when I enter one of these sites, something odd happens. It would be difficult to explain but the thing is that the site ends being useless. I once found one, mega dot nz. I registered and began using it. Afterwards, each time I used it there was no need to enter the user name and password. I just entered the site and I found myself logged in. Once, after a new install of the OS, I had to log in. But the site did not accept either the username or the password! So I had to register again, but I necessarily had to use a different email address (if I used the same one the site said that was already used). And I could then continue using the site.

Now I again changed OS. And guess what. Again the site rejected either username or password. So I'm looking for a new file sharing site (free of charge). But, I repeat, Google has not been of any help. So, if some of you could give me the URL of a decent free of charge file sharing site I would be very grateful.