I have issues in re-projecting a vector layer to match the rest of my data. I have a polygon vector layer with districts, as well as a point layer in WGS84. I know these are correct since I've been viewing them correctly in Google Maps and Google Earth in KML format. Then I have a vector layer of lines (given to me by another party) that appear far away from my other data in QGIS, and also in a completely different scale (the lines are way larger in comparison to by districts). The layer spatial reference units are also different in this layer, it is not shown in degrees as it is in the rest of my data.
I have been trying to re-project this to WGS84 (EPSG:4326), but the new layer appears in the same spot as before. I have also tried re-projecting it to WGS84 Pseudo Mercator (EPSG:3857), when I do that, the data disappears (can't find it though I try to zoom to it).
How can I alter/re-project the line-layer to match the rest of my data?