recovering network files

I appologize if this seems like stupid question to most of you but I have a problem that I do not know how to deal with! I recently replaced a networked computer with another. After replacing it, I changed it from a domain to a workgroup, ie mshome. Now it will not boot to windows. Also after changing it I was informed that 2 files that were on it are needed! How do I recover them. Serching the drive only shows the non network files?