I would first like to make sure that you don't "see" the LUNs after a simple scan.
If not, you can will have to use the Get-EsxCli cmdlet to find any detached LUNs and attach them
$esxcli.storage.core.device.detached.list()
Once you find the detached LUNs (cross-check with your input), you can use the same cmdlet to attach the LUN.
$esxcli.storage.core.device.set
but watch out there was a syntax change between 5.0 and 5.1 !
Blog: lucd.info Twitter: @LucD22 Co-author PowerCLI Reference