For Mac use below commands to stop and start Cassandra :
launchctl unload ~/Library/LaunchAgents/homebrew.mxcl.cassandra.plist
launchctl load ~/Library/LaunchAgents/homebrew.mxcl.cassandra.plist
Once cassandra is running you can validate that by opening query prompt using
➜ aseem’s Mac ✗$ cqlsh
Connected to Test Cluster at 127.0.0.1:9042.
[cqlsh 5.0.1 | Cassandra 2.2.0 | CQL spec 3.3.0 | Native protocol v4]
Use HELP for help.