Thank you all for your quick replies!

I tried everything, and the only thing I was successful at was (from my google search) pulling each line down manually.
I saved the file that way and it's fine, however, those numbers on the left are still blue. I checked and there is no filter set. I also noticed that in the similar files from previous years the same thing had happened, as if all similar files were affected all at once.
Today they are fine. I have no idea why.

Could macros have something to do with it? We have received files from other companies and as I open the file I'm asked if I want to enable macros. I might have done that! Could that have been the cause?