Could Any one Give me The Main Purpose of, Why we could use the Factory Design pattern ?.
what is the problem that this Design pattern intent to solve ?.
What is the Concept of The Factory Design pattern ?
i would be very grateful if anyone could help me on THIS issue
thanks in advance .

Google Factory Design pattern
The very first link takes you to the Wikipedia entry that answers your question.

In future please try to do at least a little research before asking someone to spend their valuable time helping you.