[Rehan]

here is the page with helpful instructions on importing data into a wordpress site.
https://wordpress.org/support/article/im...g-content/

Now this is how i was thinking. Even if it fails midway, your site db might have partial data loaded. So is there even some of the data you are trying to import, on your site somewhere, even after a failed attempt ?

If not then it is not even beginning. then may be the data xml is corrupt or not properly formatted. Why don't you install locally and experiment some to find out whats up.

Yea, i think you are right.I am also thinking that maybe the xml file is broken.I should re-download.Actually i am installing a theme which require to import that xml file.
On the other hand i don't think that is the .xml file problem because i tried importing a sample backup .xml file.