Homepage disappeared from Google Serp

[digitalkiddie]

I redirected my domain using this code in .htaccess :

RewriteCond %{HTTP_HOST} ^xxxx.com
RewriteRule (.*) http://www.xxxx.com/$1 [R=301,L]
<ifmodule mod_rewrite.c="">RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]

RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /([^/]/)index.(html?|php)(?[^\ ])?\ HTTP/
RewriteRule ^(([^/]/)*)index.(html?|php)$  http://www.xxxx.com/$1  [R=301,L]</ifmodule>

A day after I did it,  got an error in GWMT  "Google can't find your site's robots.txt" and my homepage disappeared from the result pages.

When I try to open Google cache of the homepage I got an error 404.

I generated new robots.txt, uploaded it , now the error doesnt show but still my homepage is not in the serps. Its been 3 days.  What should I do ?

Thanks in advance

"Google can't find your site's robots.txt" error? - Pro ...