Which all services did you try to restart? Did 'service bahmni-reports restart' work fine?
Have you done basic checks like memory/disk status when all the services are running? (you can do
free -m for memory, and
df -h for disk)
Another way to check if basic rersources are insufficient is by stopping other services like openerp and openelis and restart reports service to see if then it works fine.
mysql -uroot -p bahmni_reports
Another thing you could try is restarting the mysql service and then restart reports to see if that helps.
service mysqld restart
Would suggest doing this while users are not using the system to avoid disruptions.