Where is this file saved (Network Drive/ System HDD/ Shared Folder on System/ External HDD)?
Please share the screenshot of the loading screen.
Are there any recent changes made to your system? For example, any antivirus, system updates, plugins, or web extensions installed recently.
Does resetting Illustrator Preferences (https://helpx.adobe.com/illustrator/using/setting-preferences.html) help to resolve the issue? Disclaimer: Please note that resetting preferences will remove all the custom settings, and Illustrator will launch with default settings. You can also take a backup of the folders in case you want to. Location is mentioned in the article.
Also, you may try running the app in the Root/ Hidden Admin account (Mac/ Windows) and let us know if you are able to open the file.