I just started to render a project when now I have a white line all the way through a track and it is preventing some text to show. I don' t know what to do . Any help would be great
Very difficult to say where this line is coming from but if as you seem to be suggesting it is showing on the Exported video I would check very carefully on the Timeline that you don't have a "forgotten" track somewhere towards the bottom of the screen that somehow contains that line! MEP reads "upwards" through the tracks such that anything on a lower track is always placed "above" anything on a higher, i.e. it appears "in front" of objects on higher tracks.
If you mean that there is a line along the entire length of a track in the timeline then you may have activated a "Track Curve" (which is designed to control volume in an audio track) and then moved the audio track up or down leaving the title track in this position. This should not affect your video output of your title but to get rid of it in the timeline you need to vertically shift the audio track back to this position then Rt click and uncheck the tick besides "Display track curves".