#setup vi api
if ((Get-PSSnapin "VMware.VimAutomation.Core" -ErrorAction SilentlyContinue) -eq $null) {
    Add-PSSnapin "VMware.VimAutomation.Core"
}

#connect to vcenter
Connect-VIServer vcenter

$results = @()
$vmhosts = Get-VMHost
foreach ($vmhost in $vmhosts) {
    Write-Host "Checking $vmhost"
    $datastores = Get-Datastore -VMHost $vmhost | Where-Object {$_.Type -eq 'NFS'}
    foreach ($datastore in $datastores) {
        if(!$datastore.Accessible){
            $nfshost = $datastore.ExtensionData.Info.NAS.RemoteHost
            $nfspath = $datastore.ExtensionData.Info.NAS.RemotePath
            $nfsname = $datastore.Name
            Write-Host "$nfsname on $vmhost is not accessable, removing and re-adding as $nfshost : $nfspath."
            Remove-Datastore -VMHost $vmhost -Datastore $nfsname -Confirm:$false
            New-Datastore -Nfs -VMHost $vmhost -Name $nfsname -Path $nfspath -NfsHost $nfshost
        }
    }
}