The cluster service may not start because the disk signature on the Quorum disk is different from the original signature. You can change the disk signature.
To change the Quorum disk signature
Start the cluster service on one node with the -Fixquorum option in the startup parameters.
Open the Cluster Administrator and right-click the cluster, and then select Properties.
Stop the cluster services and then restart them without the -Fixquorum option.
You may run the -Fixquorum option as many times as needed to redesignate a Quorum disk signature.