Today, when I logged onto my computer, something went wrong and Windows had to repair my C: drive before it could continue to boot up. Once it did, Firefox was changed. Some of the shortcuts on the windows were missing and I couldn't get them back with the command to "Dismiss" the substitutes. More serious was my new inability to log onto any sites besides Mozilla's. I have tried restarting the computer and turning off my router and turning it back on again. All the while, my Android phone account is able to login to some of these sites without difficulty. I need to diagnose this problem and fix it. How can I do that, please?