Most likely your file is actually not using latin-1, yet your Emacs tries to decode it as if it were using latin-1. Try C-x RET r windows-1252 RET to see if it fixes your problem.
If it does, you'll want to either add a -*- coding: windows-1252 -*- cookie on the first line of the file so Emacs knows how to decode it properly next time, or (the option I recommend) you can save it using another encoding such as utf-8 which has the advantage of being reasonably easy to auto-detect: with C-x RET f utf-8 RET you can set the coding-system to use when saving the file and then C-x C-s will save it using that encoding.