If described below didn't help and you downgraded Firefox from 57 to lower version:
>>>Click here to read<<<
Update Oct 8th, 2017 #2
If you use Firefox 57+ and Speed Dial doesn't work
>>>Click here to read<<<
Step 1
Go to Settings > Privacy and Security > History section > Select "Use Remember history"
OR
Copy and paste in URL bar this address about:preferences#privacy

Step 2
Restart Browser
If it doesn't help -
Update extension to the latest version: 62.8.5 or Higher - https://addons.mozilla.org/en-US/firefox/addon/fvd-speed-dial/
This is the simples option, not always help but we encourage to try.
- Copy and paste in address bar about:support
- Select following http://nimb.ws/Vm5pjy - Rename this folder to any name and restart Firefox http://nimb.ws/awxfuW BUT don't delete it. Just rename it, for example Storage_OLD.
Here is VIDEO - http://nimb.ws/XrkKQ2
If it won't help, let us know or you have any questions, feel free to contact us team@nimbusweb.co