SQL & PL/SQL

I have a query regarding reconnection with oracle server in the middle of running application.
on start up of my aaplication i am connecting with oracle server and its connected.
i am removing the network cable in the middle while my application is running.
after few seconds i plgged it again and tried to reconnect oracle server with client where my application is still running
but it is not reconnecting and giving error "ORA- 3114 not connected to oracle" while execuiting a query.

could anyone suggest what may be the cause of the problem and solution.

i am using ODynaset class to access the database from my mfc application.
i am properly closing the database while disconnect happens and again opening database using ODatabase object its opening
successfully but while opening a table through DB class object is failing and giving the ORA - 3114 error.