solution from google searching:
2.Locate and then click the following registry subkey:
3.In the right pane, locate the
6.Restart the computer.
modified the registry . reboot. confirm that the service is running.
Next step should confirm the report service whether works. Then try to access HTTP://127.0.0.1/reportserver
other error message was prompted :
The report server cannot decrypt the symmetric key used to access sensitive or encrypted data in a report server database. You must either restore a backup key or delete all encrypted content.
It seems that lost the encrypted key . Just try to restore the key from previous backup. Ok, fixed. So, keep in mind doing a backup for report service keyis very very important procedure .