If you're having problems connecting or reconnecting the Spotify scrobbler, that is: you've definitely connected to your main Spotify account on this page but no music is being scrobbled to your profile (and private session is turned off).
Once you've done that, please try scrobbling from the Spotify desktop, mobile, andweb player, and let us know if the problem persists across all devices/apps, or just some. Please be sure to stream a track, and not play a local file.
If you're still having issues, then please let us know:
Your Last.fm username.
The version number of the Spotify app(s) you're using.
The device / operating system version you're using.