This version of Ubuntu, code-named "Natty Narwhal", was released on Apr 28, 2011 and reached End-of-Life Oct 28, 2012. Questions about unsupported versions are likely to be closed as off-topic.
Code name: Natty Narwhal
Ubuntu Flavors available under 11.04 (questions on all are allowed):
The 11.04 Ubuntu variants - Mythbuntu, Ubuntu Studio, Xubuntu and Lubuntu - are not commercially supported by Canonical.
Ubuntu Editions available under 11.04 (questions on all are allowed):
Ubuntu 11.04 reached its end-of-life on October 28, 2012.
Questions on are considered off-topic since it had reached the end of life.