There is a way to create Default Domain GPO. There are two GPO created when you promote a member computer or a stand-alone server to domain controller.
These two GPOs are :

•	Default Domain Group Policy
•	Default Domain Controller Group Policy.

These GPO are stored in the SYSVOL folder. Netlogon service creates two permanent GUID for these two GPO under SYSVOL folder:
 
            \Windows\SYSVOL\sysvol\domain.com\policies\GUID
            Domain Default GPO GUID {31B2F340-016D-11D2-945F-00C04FB984F9}
            Domain Controller Default GPO GUID {31B2F210-016D-11D2-945F-00C04FB981F1}
 
Windows OS identifies default domain policies by its GUIDs located in SYSVOL folder. These GUIDs are unique for Default Domain Policy and Default Domain Controller Policy created by default.
 
You can use the following steps to create GPOs manually:
 
1. Open ADUC
2. Right click on Domain_name.com > Property
3. Switch to Group Policy tab
4. Create a policy named "Default Domain Policy" or you can rename it if you want. AD Tools queries default domain policies by their GUIDs located in SYSVOL folder and not by name.
5. Click this GPO > Property > note down the GUID of this GPO created.
6. Go to SYSVOL folder and change the GUID to default domain policy or default domain controller policy.
7. Next you need to use a small script using ADSI to set this unique GUID into GPT of this policy in AD database. You can also edit Schema manually to do so.

You can use the ADSI Snap-in to create the GUID in GPC of that GPO.
 

 
Here are some articles that you can use to troubleshoot Group Policy:

Troubleshooting Group Policy issues in Windows
http://www.microsoft.com/technet/community/columns/profwin/pw0502.mspx
How to reset security settings in GPO
http://support.microsoft.com/?kbid=226243
Scripting GPO
http://www.windowsitpro.com/Article/ArticleID/40231/40231.html?Ad=1
Using Dcgpofix.exe:
You can also use Dcgpofix.exe to restore Default GPO.
Have a look here for Dcgpofix.exe:
http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/ServerHelp/48872034-1907-4149-b6aa-9788d38209d2.mspx
The Dcgpofix tool does not restore security settings in the Default Domain Controller Policy to their original state
http://support.microsoft.com/?KBID=833783