I want to display a popup message of date contains in text file

Thanks for accepting the previous question.

Working with CSV files is even a lot easier than getting data from Excel.

Using your example:

# import the data from the file
$data = Import-Csv -Path 'd:\Alluserreport.csv'
# filter for a specific username in the data
$user = $data | Where-Object { $_.SamAccountName -eq $env:USERNAME }
if ($user) {
    $msgBody   = "User: {0}`r`nLastLogon: {1}" -f $user.SamAccountName, $user.'Expiration Date'
    $msgTitle  = "Test"
    $msgButton = 'OK'
    $msgImage  = 'Asterisk'
    $Result    = [System.Windows.MessageBox]::Show($msgBody,$msgTitle,$msgButton,$msgImage)

}
else {
    Write-Host "Not found"
}