Vcenter Inventory Service Failed to start in Vcenter appliance or accessing vsphere webclient shows the error " Client is not authenticated to Vmware inventory service"

Issue : Vcenter appliance inventory service failed to start or accessing the vsphere webclient shows that the client is not able to authenticated to the VMware inventory services.

Where to check the logs for this :  

1.Connect the vcenter appliance with putty (ssh session) or through the console

2.Navigate to the path /var/log/vmware/vpx/inventoryservice  and check the ds log file by running the below command.
                       cd  /var/log/vmware/vpx/inventoryservice
                      cat ds.log | more

3. check to see if the database is showing as corrupt , if it is then follow the solution. This steps is for version esxi 5.5 , you can refer this vmware  kb article 2037952 for rest of the version

Solution :

1.Connect the vcenter appliance with putty (ssh session) or through the console

2.Stop the inventory service by running the command
                   Service vmware-inventoryservice stop

3.remove the data
                   rm -rf /storage/db/inventoryservice/data

4. Navigate to the path /usr/lib/vmware-vpx/inventoryservice/scripts/

                   cd /usr/lib/vmware-vpx/inventoryservice/scripts

5. run the ds-invoke.sh with the default password
                     ./ds-invoke.sh -Dvim.logdir=/var/log/vmware/vpx/inventoryservice com.vmware.vim.dataservices.CreateDb /storage/db/inventoryservice/data changeme default changeme
6.start the inventory service
                     Service vmware-inventoryservice start

7. register the vcenter appliance
                      vcenterhost=vcneterservername.yourdomaname.com

8.navigate to the directory /usr/lib/vmware-vpx/inventoryservice-registration
                      cd /usr/lib/vmware-vpx/inventoryservice-registration

9. run the vcregtool.sh
                   ./vcregtool.sh -Dvim.logdir=/var/log/vmware/vpx/inventoryservice-registration com.vmware.vim.dataservices.vcregtool.RegisterVC -action register -lookupserviceurl https://$vcenterhost:7444/lookupservice/sdk -isurl https://$vcenterhost:10443 -vcurl https://$vcenterhost/sdk/vimService -vccert /etc/vmware-vpx/ssl/rui.crt -vcprivkey /etc/vmware-vpx/ssl/rui.key -vcinstancecfg /etc/vmware-vpx/instance.cfg -vcendpointsdir /usr/lib/vmware-vpx/endpoints -vcextensionsdir /usr/lib/vmware-vpx/extensions

10. restart the vmware-vpxd service
                   service vmware-vpxd restart