All the following information is from Randall Kent's blog, it is really helpful, that is why I put it here:
"I’ve run a problem several times when .gitignore doesn’t appear to be working. The file I want to ignore is specified in .gitignore, but it always comes up as an unstaged change 
. I always end up searching the internet for the resolution, because I can never seem to remember it. Well today, I’m making a blog post about it, so it will be easier for me to find and hopefully help others with the same problem!
. I always end up searching the internet for the resolution, because I can never seem to remember it. Well today, I’m making a blog post about it, so it will be easier for me to find and hopefully help others with the same problem!
What I have discovered is that at some point in time, I mistakenly added the files that I now want to ignore to my repository. For me, this is typically a .dll in a .NET project that’s recreated on every build anyway. Since git ‘knows’ about the file, it can’t ignore it. So the resolution is simple, remove everything from git’s index and add it back which can be done with the commands below…"
git rm -r --cached .
git add .
git commit -m "fixing .gitignore"
