Dim connString As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|datadirectory|\payroll.mdb;persist security infor = false"
    Dim conn As New OleDbConnection
conn.ConnectionString = connString

it will displya the message "Could not find installable ISAM."

any one plz help

That error typically pops up when your connection string is malformed or the machine doesn't have appropriate Jet drivers installed.

First, make sure you understand the syntax of connection strings and ensure that yours is correct. At a glance it looks fine to me (but don't take my word for it), so my next step would be to check your Jet 4.0 provider's version and install all necessary redistributables/patches to get yourself up to date.

infor = false

I think that should be Info=false;

commented: Good catch +12