virtualbox.org

When i installed Windows XP in my Windows 8 PC VirtualBox I was able to connect to my server through "run" and the server address.
Suddenly I did something and I couldn't connect again, I checked the IP and i see that i received a new IP address other than my server's one.
How can solve this issue so it should return to what it was in the beginning?

What is the exact command you put in the run?
You say the IP change, why not set the IP back to its original value?
What is the server you're talking about? Something other than your host and your guest? What is its purpose?