Microsoft has stopped support for SQL server 2005 which implies that you will no longer receive security updates from Microsoft. It is highly recommended to upgrade to SQL server 2012 and later versions. You can either upgrade to later versions of SQL server or migrate from one version to another.
Refer the document provided by Microsoft on steps to upgrade from SQL server 2005. Depending on your internal environment, an appropriate method for upgrading can be chosen.
Refer Desktop Central's document for migrating from SQL server 2005 to SQL server 2012 or later versions.