My first guess would be that you have *lost* your rights somewhere in the path. If no other user has the database open, you will need create / write etc. permission on the folder where the database is stored (will create LDB file).
If you hold down the shift key to bypass the startup macro, can you open the database? If not, it's probably your rights. If yes, then are the tables located in that database, or are they linked to that database? If linked, I expect some level of authentication is hosed up.
35+ years of 'progress' -- can't we all just go wire boards again?