The nether wont load up

The nether wont load up and when i try to re log it deletes 2-5 mins of my game play.

What I expected to happen was...:
I expected to go to the nether to get some netherrack for my house

What actually happened was...:

When i tryed to go to the nether it just kept saying loading terrain then when I relog it deletes 2-5 mins of progress 
Steps to Reproduce:
1. Try to go to nether
2. Relog
3.Then 2-5mins progress deleted