I client of mine asked me to repair a ripped buttonhole in a shirt of his. I had never repaired a buttonhole before so this was a whole new learning experience for me.
First thing I did was rip out the previous buttonhole and trim the threads away from the hole.
Then I cut the hole to make it more rectangular instead of the funky shape it was and put a little fray-check along the edges.
Next, I cut little indentions into the corners so I could fold the edges of the hole to the inside like so.
After that, I took a needle and thread and carefully sewed the facing of the shirt to the actual shirt creating a patch of sorts. (don't you love my professional way of explaining things? :)
The last thing to do was make a new button hole over where the previous one was originally.
And I'm done!
This only worked because the shirt I was working with had a facing on the inside. If it didn't, I would have had to cut a patch out of the shirt from another area that didn't matter (like a pocket) or that wouldn't be seen in order for it to blend in. Other than that, all the other steps are the same.