The ptnds.zip file you have requested: Maps Levels Missions / Single Player / PT-NDS - 1.43mb is not available. Perhaps try browsing all files for the game Portal and upload any files you want to share or are missing. This is the only information we could locate:
"pt_nds - Sudden's first Portal map. Install: Just extract the "portal" directory into your first portal directory. And then you will find the map under bonus maps. Known issues: The console gets full of errors. The water reflections Here is a singleplayer Portal map from Sudden.