Your bookmarks are saved in your profile.
Have a read of this article and then follow the instructions, when you've found them just right click>copy then paste them where you can find them you can then import them back into the new install.
https://support.mozilla.com/en-US/kb...pening-firefox
Once you've got your bookmarks saved elsewhere delete the entire mozzila apps folder before re-installing FireFox
any queries come back to us.
GG