Nether portal doesnt work anymore after dying in the nether. Portal can't be removed breaking obsidian!

PROBLEM: 

The Nether Portal doesn't work anymore after dying in the nether.Also the portal cant be removed after breaking the obsidian

 

HOW TO REPRODUCE: 

1.Build a nether portal

2.Go to nether

3.Die

4.Respawn and try to use the portal again

5.Try to break the obsidian used to make the portal