Initially you speak of cells (which are on worksheets) then you mention
forms. Am I correct in assuming that you mean controls such as textboxes on
userforms? If so, check the properties of the controls and ensure that the
forecolor is not the same as the backcolor such as both white.
Also check the Enabled property but if my memory serves me correctly I don't
think you can select a control that has been disabled and hense you would not
be able to type in it.
If you were referring to cells on a worksheet the check the Protection
status in case you have it protected and can't enter anything.
