Update statement taking time to complete

Scenario :-- I executed update statement and it ran giving 1 row updated . Then putty session timed out

I reconnected to putty session and executed the select query to check whether rows has been updated or not .

It showed me rows not updated

I was worried as if happened

I reran the update query to update the rows then it hang for long time

I did following analysis

1) Checked the filesystem usage :-- Its was ok
2) Check the tablespace usage  :-- It was ok
3) Check the oracle alert log it was ok
4) Then i checked the locks in the database and i found that there is lock in the table which needs to be updated
5) I killed the Inactive session to release the lock

The update query which was hung completed by saying 0 rows updated

I ran again the select query and this time i can see the values are updated