I'm sorry to hear about this. Firefox doesn't keep backups of history, so there isn't a quick solution to restoring what was deleted. I wonder whether Firefox determined that the Places database file -- the file which stores bookmarks and history -- had become corrupted and started a new one. The only way there would be history in a fresh file if it had been restored from data in the Sync cloud (if you use Sync). In this situation, I think Firefox preserves the "corrupted" file, and it might be possible to still obtain information from it. However, this is hit or miss. Either way, the first step is to see whether you have such a file: Sometimes the settings file that stores window dimensions becomes corrupted with nonsensical values. You can rename the file and have Firefox rebuild it. Here's how: Open your current Firefox settings (AKA Firefox profile) folder using either * "3-bar" menu button > Help > More Troubleshooting Information * (menu bar) Help > More Troubleshooting Information * type or paste '''about:support''' in the address bar and press Enter In the first table on the page, on the Profile Folder row, click the "Open Folder" button. This should launch a new window listing various files and folders in Windows File Explorer. Scroll down and look for '''places.sqlite.corrupt''' or '''places.sqlite-corrupt''' and if you find one, right-click > Copy, then right-click > Paste on your desktop or somewhere else that there's no danger of Firefox modifying/replacing it. Did you find anything along those lines?