Hello, files are sometimes corrupted, if a save or a composition to take with you locally (on the desktop) does not work, you can try to recover the automatic save file. Otherwise, there is no solution.
Yes it looks a lot like a network loss and so if you really don't want to lose what you did on the part, do "file/save-as/" and save your file on your computer's hard drive.
If not, if the network has reconnected, you must re-register and replace the part on the network with the same part.
It happens to me a few times at work, it's for me, always related to a loss of network.
To check if the network is lost, just open a window with Windows Explorer to the place where your documents are saved on your network. If you can't access it through windows, it's due to a network outage.
Normally there are also temporary files that start with a dollar and are hidden. If it is possible to recover these files, they can be renamed to see at what stage of the design they were created.