Make sure it's the same crash report as before. If it isn't, post the new one.
If it is the same, I recommend updating everything, including Forge. As mentioned before in this thread, this is caused by a mod interacting with the world incorrectly, and there's not many clues in the stacktrace as to what's causing it. It's likely that this has been fixed in a later version of whatever mod is causing it.
I updated everything & now it works! thank you so much for taking the time to help me that goes to everyone else too! Much appreciated!