Magento Framework

I just migrated my website. But I got a problem.

My customers can't log in to their account. When click log in on log-in page. It should be log in on their account but it redirects the same page.
This problem arise after upgrade magento from 1.7 to 1.9
I'm very new to magento. Please Help me how to fix that?

 

Do you have some additional backend account or that one is only one?

 

http://stackoverflow.com/questions/...in-page-redirects-to-itself-without-any-error
http://www.blueclawsearch.co.uk/blog/2013/12/12/fix-customer-cannot-login-to-magento-1-8-1/

 

Go to: /app/design/frontend/default/template-name/template/persistent/customer/form/

and paste

<input type="hidden" name="form_key" value="<?php echo Mage::getSingleton('core/session')->getFormKey(); ?>" />

after

<ul class="form-list">

That should fix it.