1. Open Firefox. 
   2. Click on the Library icon (the three horizontal lines) in the top right corner. 
   3. Select Bookmarks and then click on Show All Bookmarks at the bottom. 
   4. In the Library window, click on the Import and Backup button. 
   5. Choose Restore from the dropdown menu. 
   6. You will see a list of available backups. Select a date before you lost your bookmarks and click on it to restore. 

   1. Open Firefox and click on the Menu button. 
   2. Click on Sign in to Sync if you are not already signed in. 
   3. Once signed in, your bookmarks should sync automatically. 

   1. Type about:support in the Firefox address bar and press Enter. 
   2. Under the Application Basics section, find the Profile Folder and click on Open Folder. 
   3. Look for a folder named bookmarkbackups. You may find JSON files that contain your bookmarks. 

   1. Go back to the Library window (as described in step 1). 
   2. Click on Import and Backup and select Restore. 
   3. Choose Choose File and navigate to the JSON file you found in the bookmarkbackups folder. 

'''1. Check for Backup Files''' Firefox automatically creates backup copies of your bookmarks. You can restore them using the following steps: 1. Open Firefox. 2. Click on the Library icon (the three horizontal lines) in the top right corner. 3. Select Bookmarks and then click on Show All Bookmarks at the bottom. 4. In the Library window, click on the Import and Backup button. 5. Choose Restore from the dropdown menu. 6. You will see a list of available backups. Select a date before you lost your bookmarks and click on it to restore. '''2. Check Firefox Sync''' If you had Firefox Sync enabled, your bookmarks might be saved in your Firefox account. To check: 1. Open Firefox and click on the Menu button. 2. Click on Sign in to Sync if you are not already signed in. 3. Once signed in, your bookmarks should sync automatically. '''3. Look for Manual Backups''' If you have manually backed up your Firefox profile or bookmarks, you can restore them from that backup. Look for a file named bookmarks.html or similar in your backup location. '''4. Check the Profile Folder''' If you haven't found your bookmarks through the above methods, you can check your Firefox profile folder: 1. Type about:support in the Firefox address bar and press Enter. 2. Under the Application Basics section, find the Profile Folder and click on Open Folder. 3. Look for a folder named bookmarkbackups. You may find JSON files that contain your bookmarks. '''5. Restore from JSON Backup''' If you find a JSON backup file: 1. Go back to the Library window (as described in step 1). 2. Click on Import and Backup and select Restore. 3. Choose Choose File and navigate to the JSON file you found in the bookmarkbackups folder. '''6. Use Data Recovery Software''' If none of the above methods work, you might consider using data recovery software to try to recover lost files from your hard drive.