The majority of Magento issues are usually caused by an invalid cache or the need for re-indexing. If you are experiencing any problems with how things work or display on a screen in Magento then the first step is to clear your cache and re-index your data.
When making certain changes to Magento in can invalidate your cache.
There are two ways to clear the cache in Magento:
Through the Magento Admin Panel:
Log in to your Admin Panel account
Go to the System -> Cache Management section
Click on the Flush Magento Cache button
Using SSH/FTP or the cPanel File Manager
Delete the contents of the var/cache/ folder using the following SSH command:
rm -rf var/cache/*
Delete the folder var/cache/ through your FTP client or using the cPanel File Manager.