I stored data (road network: line features) on OpenGeo Geoserver compilation and when I tried to display these in openlayers or GeoExt, they are shown as point features.
First things frst, double check that the data is actually lines and hasn't been changed into points without you noticing.
Secondly, are you using WMS? If so then, as @iant mentioned, the GeoServer style is probably set to a point style, rather than a line style.
In your GeoServer admin pages, go to the layers page and open the layer that you are having trouble with. There should be two tabs, Data and Publishing. Go to Publishing and scroll down to Default style and make sure that there is an appropriate style set that can handle lines. I think GeoServer comes with some default line styles. It should give you a legend once you've selected a style showing what styles that SLD has. Change it to something more appropriate then open it up in the Layer Preview and see what you get. If you're still having trouble you'll need to give us some more information!