@Tomkitten,
Does this look like what you are trying to describe? I used my own My Documents folder and scrunched up the columns to the left.
If so, take a look at the column labels where I have drawn some blue circles. Between each column there is a faint dividing line that you can grab with your mouse pointer and slide back and forth to adjust the width of the columns. There may be multiple columns scrunched up on top of each other so you may need to widen several columns to get it straightened out again.
By the way, so that we can get some common terminology going, what you are seeing when you open your My Documents Folder is the Windows Explorer (it used to be called the File Manager).
If what I described and the suggestion I gave isn't it, let me know and we'll try something else.