After shutting down the database and making sure that no other user is on the
database, go to the folder holding the .mdb file. Is there a .ldb file with
the same name? If so try to delete it and reopen the database.
Can you delete the .ldb file? If not, that's the problem. You need read,
write, create, and delete permissions for the entire folder not just the
database file.
If you can delete the .ldb file, does the database start up again? If so,
someone else is locking up the .ldb file.
If you can't start the database file, can anyone else? It might just be your
computer. Can you open and close any other database file successfully?
Go to Tools, Options, General Tab and turn off Compact on Close if enabled .
While there turn off Name Autocorrect. You'll be glad that you did.