Sheet blocked by macro

My macro sometimes goes wrong. Then I try deleting the whole sheet contents and this happens:
- The contents gets deleted all right; but
- the sheet remains all selected (darkened) and blocked, and
- the headings of rows and columns all disappear, as do the cell-contour lines;
- the cell address display (top left corner) says that the cursor has moved to the very bottom of the sheet.
The appearence is this
Screen-Error.JPG

insted of the usual
Screen-Correct.JPG

What can have gone wrong, and how can I restore normality?
Thanks for any help.
ACA

Thanks for attempting to help.
The macro in fact does a lot of different things, among them filtering data.
Sorry I cannot offer further assistance.
ACA

Thank you, Zer0Coll. In fact the macro itself performs all its functions well throughout. It's when attempt to do further work on that sheet that I find it behaves in a faulty way.

And thank you, Special-K. I understand you find I'm not giving clues that are specific enough. All I can say is that it's not because I feel apathetic about it; it's that I don't see what I may offer that can be useful. But you're right to leave me and devote your efforts and skills to more productive queries. Thanks for your two replies.
ACA