Step 1: Go to the help menu by clicking the main menu button depicted by three horizontal lines.
Step 2: Under the help menu, click on troubleshooting information
Step 3: Click on refresh Firefox button in the upper right corner of the page you have opened
Step 4: Click on the Refresh Firefox button in the new confirmation page that comes up
Step 5: You will receive a prompt saying that your profile is imported successfully. Click on finish and the Firefox will import your preserved profile configurations and reopen with all default settings