Hey all this is the first time of me posting on this forum.

I have a wo that I was just playing on last night with some friends and it was great.

However today we ventured out into the world and unfortunately the server crashed.

Now every time I load up the world again on the server. It stops preparing the world at 0%. There are mods in it, but it does load a new world if I got rid of the new one and the mods ran perfectly when we used it before. It's just now that the world tries to load. We made 4 hours of progress, and we don't want to lose the world. If anyone has any tips for this, I would greatly appreciate it.

It sounds like the names used to distinguish two world generation code is the same, which confuses the system and causes it to crash because that's not how it's supposed to happen. What you could try doing is experimenting with alternative mods by deleting different ones until you find the culprit 

If the server crashed, it may have corrupted the world (I had this happen before) and you might have to restore from a backup.

You should post the debug log from the server, it should contain information that will help track down the issue, without having to use too much guesswork.