Did you choose the customized version of Bootstrap? There is an issue that the font files included in the customized package are broken (see https://github.com/twbs/bootstrap/issues/9925). If you do not want to use the CDN, you have to download them manually and replace your own fonts with the downloaded ones:
https://netdna.bootstrapcdn.com/bootstrap/3.0.0/fonts/glyphicons-halflings-regular.svg https://netdna.bootstrapcdn.com/bootstrap/3.0.0/fonts/glyphicons-halflings-regular.woff https://netdna.bootstrapcdn.com/bootstrap/3.0.0/fonts/glyphicons-halflings-regular.ttf https://netdna.bootstrapcdn.com/bootstrap/3.0.0/fonts/glyphicons-halflings-regular.eot
After that try a strong reload (STRGCTRL + F5), hope it helps.