my website is banned by google help plz

I change my website to wordpress it's been three weeks and I disable permissions for the search engines in robots.txt file (with fault) and now my website is banned by google

help plz

Try to submit your site through google webmaster tool.
Login to webmasters,add your site and now check for the errors its showing there if any.
Then go to health-->Fetch-->Enter your site URL--> click on Fetch-->Once its success then click on index.
Hopefully they will index your site once again.
If this dont work then better try to contact google and fill up the request form.

I don't thing it's banned, Google probably hasn't recrawled it since your robots.txt error. Build some backlinks to it to help Google recrawl it and it will get indexed again.

Try this, put the following in your header until Google re-indexes you, usually within a day or so, good luck:

<title>The name of your website goes here</title> <meta name="title" content="The name of your website goes here" /> <meta name="description" content="Meta Description" /> <meta name="keywords" content="keywords, keywords, keywords " /> <meta name="GOOGLEBOT" content="NOARCHIVE" /> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="robot" content="index,follow" /> <meta name="revisit-after" content="2" />