What will happen if I delete 'page.tpl.php file'? Is there any alternative for this file?
page.tpl.php file is used to render your page body content (i.e. content inside &lt;body&gt; tag). Below is one line description of file on api.drupal.org.


  Default theme implementation to display a single Drupal page.


If Drupal is not able to find page.tpl.php file inside your theme, then it will use one of the following file:


If your theme has Parent theme, then Parent theme page.tpl.php file.
If no, file provided by system module.


If you're using version control system like GIT, Bitbucket, etc. you can revert your file from last commit. If not you will need to create new file and do necessary changes