Hi I recommend you have a read of this [https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings article], that will walk you through how to refresh Firefox. You may wish to take a back up of your profile before hand. You can read how to do this [https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles#w_backing-up-your-profile here]. I hope this helps, but if not, please come back here and we can look into a different solution for you.