Apologies if this concern was already raised because I didn't find it (somehow).
Till few days back I was running my WP site happily. Recently I installed/activated a new theme and noticed that after theme activation my index.php automatically went blank
I restored index.php from WP source code but as soon as I refresh my site, it automatically again went blank.
If I restore index.php and move back to my old theme, index.php remain intact (keep code) and site works fine.
I tried uninstall - install of new theme multiple times but it didn't worked.
I understand that I downloaded new theme from not so reliable source. Is there any way by which I can find the notorious code which is creating this trouble for me? or put a permanent fix?