If it's a form window, you can open the Window Tweak wizard.
Just doing that should give the window scroll bars and restore your ability to resize. Then you save.
If it's the data sheet, hold the control key down, and use the View menu to open another window. The new window should open with scroll bars. Then you close the data sheet window, and return to the View menu. Without using any modifier key this time, choose the data sheet. That will put the data sheet in your current window with scroll bars. Resize to taste, and save.