In SharePoint 2007 after running a Stsadm to backup a site, I was missing all the menu items in Site Actions. After spending time and searching in Google, I found a solutions.
This is what I see in Site Actions
If you see above problem, this is what you have to do
Go to Central Administration | Application Management
Under SharePoint Site Management click on Site Collection Quotas and Locks
Select your site application
You may see Read Only (blocks additions, updates and deletions) is selected
Uncheck this and select Not Blocked. This will solve your problem.