SharePoint 2010 Lock/Unlock site collections

You can apply locks to a site collection to prevent users from updating content or you can temporarily prevent users from accessing the site collection.

To unlock/Lock a site collection follow the below steps.

• In Central Administration, click Application Management.
• On the Application Management page, in the Site Collections section, click Configure quotas and locks.
• Use the Select Site Collection page to select a site collection.
• Select Read-only (blocks additions, updates, and deletions) to prevent users from adding, updating, or deleting content.
• Type a reason for the lock in the Additional lock information box.
• Click OK.