Rich text apostrophes aren't printing right

I'm echoing text and all the apostrophes look like this â so the word it's is printed as Itâs. Is there something I need to do to the text, like encode it or decode it or something. How can I fix this?

note: actually, it seems even stackoverflow wouldn't print the characters I see. The apostrophes are changed to the â开发者_JAVA百科 you see above, and 2 boxes next to it which contain the numbers 0080 and 0099. But stackoverflow deletes them from here.

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I am not a php guy but it might be possible that development IDE would not support UTF-8 or encoding other than ANSI. Workaround is to copy the original text and paste it into the text file which has ANSI encoding. Fix your missing characters manually and then copy the text from that file into your development IDE. If you don't want to do this then you have to enter the actual decimal or hex values of those problem characters.