Looked at the ULS logs and found some access denied errors which tells me that there is some security issue. Started to review the site permissions and noticed all Out Of Box SharePoint Groups were deleted and I released something is wrong with “Style Resources Reader” SharePoint Group and added this group manually to the site with Read permissions and this didn’t help.
I found a couple of Blog posts suggesting to grant read access to Style Resources Reader” SharePoint Group to the Master Page Gallery and the Style Library. Go to Site Actions à Site Settings à Site Administration and click on Content and Structure à Master Page Gallery àEdit Properties and grant read access to Style Resources Reader” SharePoint Group, repeat the same to the Style Library as well.
Lessons learnt is not to delete the OOB SharePoint groups
