If any command is not working in hbase please follow below steps to restart Hbase shell

1)  cd /usr/lib/hbase-0.96.2-hadoop2/

2)  sudo rm -r hbasestorage/*

3)  sudo rm -r logs/*

4) ./bin/start-hbase.sh

5)  hbase shell

you can also execute below command to alter table schema

1. Creating table MyTable with column family cf1

create 'MyTable', 'cf'

2. Adding recoreds in MyTable

put 'MyTable','row1','cf:name','abhishek'

put 'MyTable','row1','cf:name','andy'

put 'MyTable','row2','cf:name','Ajay'

3. Disable table to make changes in table schema

disable 'MyTable'

4. Alter table, here we are adding one more column family naming cf2

alter 'MyTable', {NAME => 'cf2'}

5. Enable table

enable 'MyTable'

6.  Adding recoreds in column family cf2 in MyTable 

put 'MyTable','row3','cf2:name','Ajay'


7. Now do scan in MyTable and you can see the changes


scan 'MyTable'

Now by executing above steps will change my table, you can refer below screen shot for your reference