I am not able to installing audacity2…3.1 in my ubuntu 14.04.
Can yo please help me? 
Ubuntu 14.04 is very old (released in 2014), and is beyond its mainstream support (Extended security maintenance only).
I’m not aware of anyone providing builds of Audacity 2.3.1 for Ubuntu 14.04.
It “may” be possible to build Audacity 2.3.1 yourself on Ubuntu 14.04, but you are likely to face a lot of problems due to out of date dependencies. My recommendation would be to update your operating system (for example, Ubuntu 18.04 LTS).
How can I download 18.04?
https://www.ubuntu.com/download/desktop
Please note that this forum is a support channel for Audacity software.
For Ubuntu community support see: https://community.ubuntu.com/t/community-support