Please check the following.
1) check if the font files are in your project in visual studio (i.e. event the files are in the the project folders in Explorer doesn't mean it is in visual studio project, see if you can view it in your solution explorer)
2) if you can see it in your solution explorer, right click on it and see if you see an option called Include In Project
. if you see this, click on it and it will include the file into your project. Instead, if you see Exclude from Project
then it's in your project.
3) right click on the font file again and see if the Build Action property is set to Content.