Greetings.

Today, surprisingly, all DWG files that I open appear blank and black in all viewports.

These files were not imported; all were created from scratch by me on this computer.  Some of the files are several years old, some were opened just last month.  Even in a new file, I cannot see anything, including the cursor.

I am not 2D CAD savvy nor up on all the features and functions.  Most likely I changed inadvertently changed something last time I was in.

Any suggestions?