i solved the problem

You can get the Turkish locale of Firefox Nightly channel builds at https://www.mozilla.org/firefox/all/#product-desktop-nightly (may need to "Select your preferred language") You can also use Language Packs as this allows you to use two or more languages on the user interface with one Firefox install. https://support.mozilla.org/en-US/kb/use-firefox-another-language Note the more unstable Nightly channel is meant more for developers and testers in mind as it can get checkins and updates twice a day. This can sometimes lead to issues until things are fixed, finished or reverted.