Move Data From one column to another in same table

Okay, after I got everything imported, I found that a few thousand columns had "Shifted" on me. So now I am trying to "Shift them over" to where they need to be.

I did this:
INSERT INTO dbo.TABLENAME (COLUMN_NAME_TO_BE POPULATED)
SELECT COLUM_NAME_OF_INFO_TO_BE_MOVED
FROM dbo.TABLENAME
WHERE MFG = 'MANUFACTURER_NAME' AND PN LIKE '8888888888'
GO

I populated the PN column with 8888888888 to use as a reference point, and the MFG column already was populated with the correct name, so I was using those as my unique reference points.

Other columns that have the same MFG name are correct, so I have to use two unique identifiers to specify the actual data that needs to be moved.

It inserted 'NULL' in the whole table after I ran it in the Query Analyzer. It appeared to disregard the WHERE statement all together
Any ideas on what I am doing wrong here?

Is there a way to move the data from one column to the next one over by specifying other WHERE criterias?

Well, it was good to get the question out there, now here is the solution I did that worked:

SELECT COLUM_NAME_OF_INFO_TO_BE_MOVED
FROM dbo.TABLENAME
WHERE MFG = 'MFG_NAME'AND PN LIKE'8888888888'
UPDATE dbo.BELLCORE
SET COLUMN_NAME_TO_BE POPULATED = COLUM_NAME_OF_INFO_TO_BE_MOVED
WHERE MFG = 'MFG_NAME'AND PN LIKE'8888888888'
GO

I checked the results and it worked like I wanted, I think. SO far so good....... Thank you all for being the sounding board for frustrating moments.............