I have had trouble in the past with files not opening.
What worked for me in some cases was to open another file that is OK.
Ideally one based on the same template so it has the same layers, linetypes, etc.
Now the trick is not to close that file but to simply open the corrupt one from the menu.
Th existing file will close and the corrupt one will hopefully open.
To me it seemed there was some setting missing from the corrupt file that wouldn't allow it to work but having the other file open first set these values - whatever they wer.
I hope this works for you.
Barry.
One of the forum moderators.
Versions 6.5 to 27
i7-10700 @ 2.9Ghz, 32GB ram, GeForce RTX 2060 (6GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11