Yep, Lee is correct. Your only option is finding some software with OCR capabilities so it can "read" the document and guess what the characters are meant to be. OCR is always a bit hit-and-miss depending on the image quality and size of the file, so there's usually still some hand-editing that needs to be done. You can try doing a web search for OCR to see if there's any freeware out there, or if you're lucky enough to have Adobe Acrobat installed, you can use it's built-in OCR feature.
Just remember to always ask yourself this... Could you have just re-typeset the document in the time it took you to hunt down a "quick" fix? lol... I bust myself with this all the time... 😀