how to minimize vb.net code

You have two blocks of code very similar, create a method (with proper arguments) and call it twice.

BTW you may also discard the SqlParameters, since you are using constants (write the constants directly inside the queries).

First thing there is nothing wrong with what you did.

But since you asked :)

First I would create a stored procedure

CREATE PROCEDURE [dbo].[Asset_Service_Master_Get_Counts]
    @CaseStatus VARCHAR(50) = NULL, --You'll need to add the correct types.
    @CallClosed VARCHAR(50) = NULL,
    @BillingComplete VARCHAR(50) = NULL
AS 
    BEGIN
        SELECT  COUNT(*)
        FROM    Asset_Service_Master
        WHERE   CaseStatus = COALESCE(@CaseStatus, Asset_Service_Master.CaseStatus)
                AND CallClosed = COALESCE(@CallClosed,Asset_Service_Master.CallClosed)
                AND BillingComplete = COALESCE(@BillingComplete,
                                               Asset_Service_Master.BillingComplete)
    END

GO

Here is the method I would use.

Public Function GetCount(Optional ByVal caseStatus As String = "", Optional ByVal callClosed As String = "", Optional ByVal billingComplete As String = "") As String
    Using cn As New SqlConnection(connectionString)
        cn.Open()
        If cn.State = ConnectionState.Open Then
            Using cmd As New SqlCommand("Asset_Service_Master_Get_Counts", cn)
                cmd.Parameters.Add(New SqlParameter("@CaseStatus", IIf(caseStatus = "", DBNull.Value, caseStatus)))
                cmd.Parameters.Add(New SqlParameter("@CallClosed", IIf(callClosed = "", DBNull.Value, callClosed)))
                cmd.Parameters.Add(New SqlParameter("@BillingComplete", IIf(billingComplete = "", DBNull.Value, billingComplete)))
                cmd.CommandType = CommandType.StoredProcedure

                Return cmd.ExecuteScalar().ToString
            End Using
        Else
            Return String.Empty
        End If
    End Using
End Function

hii,

use this code

Public Sub setvalue()
        Dim para(1) As SqlParameter
        para(0) = New SqlParameter("@temp", "pending for client approval")
        tb_PendingForClientApproval.Text = getValue("select Count(*)  from Asset_Service_Master where CaseStatus=  @temp ", para)


        Dim para_2(2) As SqlParameter
        para_2(0) = New SqlParameter("@tp", "yes")
        para_2(1) = New SqlParameter("@temp", "")

        tb_CalledClosed.Text = getValue("select count(*)  from Asset_Service_Master where CallClosed= @tp   AND BillingComplete=@tmp ", para_2)

    End Sub

    Public Function getValue(ByVal Query As string,ByVal para() As SqlParameter) As String)
        Try
            cn.open()
            cmd = New SqlCommand(Query, cn)
            cmd.Parameters.AddRange(para)
            Return cmd.ExecuteScalar().ToString

        Catch ex As Exception
        Finally
            If (Not cn.state = ConnectionState.Closed) Then
                cn.close()
            End If
        End Try
        Return ""
    End Function

may be your Question is not so clear
but
you can try like this also

cn.open()
 Dim tp As String = ""
        Dim tmp As String = "pending for client approval"
        If tmp = "pending for client approval" Then
            Str = "select Count(*)  from Asset_Service_Master where CaseStatus=  @temp "
        Else
            tp = "yes"
            tmp = ""
            Str = "select count(*)  from Asset_Service_Master where CallClosed= @tp &  AND BillingComplete=@tmp   "
        End If
        md = New SqlCommand(Str, cn)

        cmd.Parameters.Add(New SqlParameter("@tp", tp))
        cmd.Parameters.Add(New SqlParameter("@tmp", tmp))

        tb_CalledClosed.Text = cmd.ExecuteScalar().ToString

        cn.Close()

Declare All other Variables as per your Requirement