Your ConnectionString should be as follows
If you are using .accdb(Access Office 2007)
"Provider=Microsoft.ACE.OLEDB.12.0;Data source=yourDatabase.accdb;Jet OLEDB:Database Password=yourPassword"
Similarly if you are using *.mdb file your connectionstring should be look like as follows
"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=yourDatabase;
Jet OLEDB:Database Password=yourPassword;"