It may not be locked but may be disabled? Or does it appear normal and not greyed out? In that case, open a new form in design view and copy the control to it. If you can type in it in form view, the other form may be corrupt. If you can't type in it in the new form, the control may be corrupt. Then again, you wrote
Why is it that I cannot edit any of my controls.
but then posted as if the problem is with one control, so I'm leaning towards corrupt form.
I take it that this "an unbound textbox which is Editable" means your form Allow Edits property is set to yes/true.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.