Here is a thread with solutions for missing server lists:
http://forums.taleworlds.com/index.php/topic,116878.0.htmlSometimes servers stop showing up for apparently no reason, and sometimes they start showing again, so you can just wait and keep pressing refresh.
If you do get servers, remember to add them to favourites, that should stop them disappearing again.
If none of the fixes in that thread work, you can try getting someone you know who does get a full server list to make a profile for you, add all the servers you want to play on to the favourites for that profile. Then get them to send you their profile.dat file and replace your one with theirs, hopefully you should get those servers saved as favourites so they won't go missing.
The profile.dat file is in AppData/Roaming/Mount&Blade Warband
AppData might be a hidden folder, google how to find it for your version of windows (I think %AppData% in the search thing should get it)
Also, check that nothing is blocking M&B from working, like a firewall.