FileMaker Pro 10 can’t convert databases that were created with FileMaker Pro 1.x or 2.x. For more information, see
Converting FileMaker Pro 1.x and 2.x databases.
Try recovering the original file using your version of FileMaker Pro. Then open the recovered file with that same version, close the file, and then try converting it with FileMaker Pro 10.
Passwords are case-sensitive in FileMaker Pro 10. Make sure you enter your password exactly as it was created in a previous version of FileMaker Pro. If you are the owner of the original file or the database administrator, open the original file using a previous version of FileMaker Pro, and look at the password in the Define Passwords dialog box. If you are not the owner of the file or the database administrator, consult your database administrator for password information.