How To Reset or Revert Group Police Object To There Default
Some time the group policy on window servers can break, it can be after bad domain upgrade or file corruption or even IT mistake . The domain can suffer greatly from that . In order to restore the values to there default you can use command line “dcgpofix” which will reset all the group policy objects :

You can reset specific target for example to reset domain GPO :
dcgpofix /target:Your_Domain_FQDN
To reset the dc GPO :
dcgpofix /target:Your_DC_FQDN
To Reset both :
dcgpofix /target:both
Good Luck