Quite simple really, your movie seems to be playing in the composition named "artur artz - say no more". You are rendering your second composition which seems to have nothing in it.
Also, just a suggestion, never render directly from after effects. Always export to adobe media encoder, because you'll be able to export to the h.264 format with faster renders, and smaller file sizes.
Just follow these steps:
1. Open the composition that has your video in it.
2. Set the preview movie size from "quarter" to "full".
3. File > export > adobe media encoder.
4. Change the codec to h.264 and adjust the resolution to be 1080p; You can do this by clicking the blue text in the preset column.
Hi... Now I did that now atleast I get sound coming out from the finished export in media encoder however the screen is still black
Wait a minute...you see that blue grid next to the name of your mov file? Simple right click it and click on turn off. Whenever, you have that blue grid, it will not render the video in the final result.
Here is another thread with someone who also has the blue grid: strange blue grid
I don't typically see this when I'm animating, but you will want to turn that off whenever you import a video and want to actually see it in the finished result.
Also, do still use the method for rendering I mentioned in my previous post as well, seeming as it is a lot more efficient.
That "strange blue grid" is there to mark that layer as a guide layer (as mentioned in Draceon's link). It's so you can animate or work with a reference, but that reference won't render. See AE's help files for how to use guide layers.
Thank you so much for your help!!