Server not starting

hello, Im quite new around here.

this morning I tried to run my server, but it kept stopping while it was "starting".

Im no programmer, but i looked into the logs and it said something about:

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forge mod Loader detected that the backup level data is being used

This may happen due to a bug or corruption, continuing can damage your world beyond repair or lose data / progress.

it is recommended to create a world backup before continuing.

Run the command /fml confirm or or /fml cancel to proceed.

alternatively start the server with -Dfml.queryResult=confirm or -Dfml.queryResult=cancel to preselect the answer.

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Full log

Like I said i'm quite new to running a server. But, I'm greatly enjoying myself and I really don't want to loose all the progress me and my friends have made so far.

Any help with getting the server back up and running would be fantastic. Thank you.

Ok you can close this post, i think i figured it out and got my server up and running again.

if you think you may be having a similar problem, this is what I did:

I downloaded the world and opened the zip file.

in the zipfile there was a file called Level_old.dat or something like that.

get rid of the old part and rename it to Level.dat.

then re-zip the file then upload it again.

that's all I did.

Hopefully that can be of use.

OK, new problem now. Now it says my save is being accessed from another location, aborting.

i had replaced the level.dat file in the world. but I just restarted the world.

Ah, I see. When i got the first error message in the first post, I hadn't touched anything yet. Even though I just created a new world and told my friends that there was nothing else i could do, Im still not sure how or why my world got messed up the first time. Do you know what I should've done instead of try and edit the files? Just in case this happens again.

alright, thanks for the help. I really appreciate it.