again, this is pretty easy to debug. example:
Apache server:
login to your server and:
find Apache error log location:
first get the configuration file:
~/#: httpd -S
VirtualHost configuration:
*:80 is a NameVirtualHost
port 80 namevhost example.com (/etc/httpd/conf/httpd.conf)
Syntax OK
look for ErrorLog path:
~/#: grep ErrorLog /etc/httpd/conf/httpd.conf
ErrorLog "/etc/httpd/logs/error_log"
use tail to read the latest log entries:
~/#: tail -f /etc/httpd/logs/error_log
Nginx server:
~/#: cd /var/log/nginx
~/#: tail -f error.log
Magento internal logs:
if you are not sure where is the shop installed:
~/#: updatedb
~/#: locate app/etc/local.xml
~/#: /var/www/html/shop.com/app/etc/local.xml
if you are the owner or you know where is the shop:
~/#: cd /var/www/html/shop.com/var/log
~/#: ls
~/#: exception.log system.log
~/#: tail -f system.log
open your browser and go to your admin page (or any page that fails or blank, etc), click it few times, press F5, etc.
and see your error log fills-in with error messages.
but obviously you have to flush the cache storage and clear opcode cache as well,
dont forget about memcached and redis :)
p.s: This example uses the default options.
Your server may use different configurations and paths.
There is no built-in uninstaller for Magento.
If you followed best practices while developing Magento, all of your Magento-related files should be located under the same root folder in your filesystem, and all Magento-related database tables should be located in the same database.
If that's the case, uninstalling is as simple as deleting the files in the filesystem:
sudo rm -rf <magento root dir>
And dropping the database associated with Magento:
mysqladmin -u[username] -p[password] drop [database]
If you can't remember the name of the database your Magento installation uses, you can find that in app/etc/local.xml in the dbname node. You'll also find relevant login information there.
If you placed files or tables outside the bounds of Magento's root directory and database, you'll have to identify them and delete them manually.
Best Answer
There is simple step to do that but i that process maybe you lose some data of that extension.
First
Try to upgrade it by pasting the new version through zip the extension will be update automatically.
Second
You want to remove the extension and install new one. go your core_resource table and delete the module entry from their. Paste new version and clear you cache.