You must know the password.
Old versions used password only.
Newer (7 and up) versions use User and Passord
Old version databases can be opened with old password entered into User AND Password.
If you do not know the password, (and you SHOULD) you are stuck with trying a FMP password cracker program, or talking to Filemaker Support.
If there was no password, hitting return should open it..
David thank you for your advise...I use my old password in the name and the password for the new FMP version 11 and it worked fine...Thank you...
Glad it worked.
Write passwords down in three places (one on a piece of red paper and tape to the ceiling)