I am getting error `failed to connect to 127.0.0.1:7199: connection refused` when I do a `nodetool status` on my RHEL machine. It was working fine until yesterday but today it suddenly started giving this error. I did not make any changes to the configuration files. 

I have DSE installed and properly configured as it was running fine till yesterday from past 3-4 months. The cassandra.yaml has the cluster name, seed, rpc address, rpc port, listen address all configured correctly. Also I set `-Djava.rmi.server.hostname=<server ip address>;` in cassandra-env.sh. Still did not work. Nor am I able to connect to cqlsh, nor my SOLR is accessible after this. Also I have allowed all ports on my security group on my machine to check if it is any port problem but it is not. 

Any help would be appreciated.