Summarizing, i uninstalled nightly (mozilla web browser) and at the process there was an option related to if i wanted to delete all my bookmarks and history, i selected it. Since it was a different browser from firefox i thought it wouldn't do any bad, because, as i said, it was a different browser, therefore firefox should have a file of its own about its history and bookmarks (my main browser is firefox, only used nightly for 5 min). After the uninstall i procceded to continue navigating on firefox, after a while, suddenly the browser crashed and it appeared an error (something related to "app" i think, i cant remember). Next I reopened firefox and it was like new, a tab opened with the title "First run" and all my history and bookmarks had vanished. Which made kind off depressed because i had hundreds. I hope there's a solution, please.