Check if Browsec is installed
Open to your add-ons list and check if Browsec is there. If it's disabled, click the switch to activate it:
If you don't see Browsec in the list, visit the Browsec's page in Firefox Add-Ons. You will see 'Add to Firefox' there, click this button:
Follow the on-screen instructions. If you have doubts, you can refer to this guide.
If the blue button says 'Remove', then Browsec is installed already. Here are your next steps:
Check in the Overflow menu
Click and look for Browsec:
If you see it, right-click and click 'Unpin from Overflow menu':
No Overflow menu, or Browsec is not there
Right-click the toolbar and click Customize Toolbar:
Check if Browsec is there. If you see it, drag it back to the toolbar:
No Browsec in Overflow or in Customize
Time to refresh your Firefox settings. After refreshing, you'll have to reinstall Browsec and all the other add-ons. That's why you should use this as a last resort.