Oracle service crash and could not connect to database

Oou dear...
monday morning attack from oracle service that found crashed (dead).

I was just having my application demo and tested with my client/user on friday afternoon.
but when i want to start my job this monday morning, my apps could not connect to database.

the error description is ORA-00600.
Another problems was i could not login to Database control on my database server even when user and password are correct. hmmpphh...

Then i found this solution from oracle community (https://community.oracle.com/thread/840511?tstart=0)
the solution steps are quite easy to follow.
1. open your command prompt
2. go to sqlplus (provide your user credential)
3. write this on sql>

• shutdown 

• startup mount;

• alter database open;

Run the application again. than whoalaa.... it back to normal. phfiew...

*taken from https://community.oracle.com/thread/840511?tstart=0