What form would I need to get in order to find out how much federal withholdings was held when I received a hardship loan, and or cashed out my 401k (mind you it was in the year 2004) and all I can remember is the name of the retirement agency, which I think it merged,or been renamed

You can get the agency information by requesting a tax script for 2004 from the IRS. They will have the Form 1099-R information on the tax script.

Call the IRS to request the tax script; it is free and will be mailed to you in about two weeks after the call.