Facebook and Twitter font changed, how do I get the old one back?

I read that the font used was Lucida Grande, so I downloaded it. It's changed how Twitter and Facebook looks font-wise, and I want to get the old font back. However when I remove the font, there isn't a default one to replace it? All the letters are jumbled up.



How can I fix this and get back to the old font?



Looks the same in Chrome and firefoxFacebook and Twitter font changed, how do I get the old one back?
try this clearfont thing, google it, mine used to be like that