Why am I unable to send or recieve text messages from my iPad

By itself, the iPad can only send messages to other iMessage users. However, if you connect it to an iPhone logged into the same Apple ID, you'll be able to send messages to SMS users. On the iPhone, go to Settings>Messages>Text Message Forwarding and select the iPad.

See this article for more information:

Use Continuity to connect your Mac, iPhone, iPad, iPod touch, and Apple Watch - Apple Support

See if this helps: https://support.apple.com/en-us/HT204065