Hi Praveen,
Do you set quotas or locks for the site collection in Central Administration?
Quotas and locks are two ways of controlling access to site collections. Using locks, you can manually prevent user access. Using quotas, you can prevent users from adding content to a site collection, or you can send e-mail warnings to the site collection
administrator when specified disk space thresholds (in megabytes [MB]) are exceeded.
More information about quotas and locks in SharePoint 2010:
https://technet.microsoft.com/en-us/library/cc263050%28v=office.12%29.aspx?f=255&MSPPError=-2147217396
Please try to select "Not locked" for Site Lock Information and uncheck "Limit site storage" for Site Quota Information.
Then go to manage web applications->[your web application]->Service Connections, make sure Web Analytics service is checked.
After that, access some libraries or lists or pages, then check web analytics report.
Thanks,
Wendy