While programming an add-in for Excel 2010, I suddenly realized that I was no more able to automatically fill and drag-drop cells. In excel, when we select a cell and move our mouse to the border of that cell, the cursor changes and it is using this through which we can drag-drop or auto-fill but in my case this stopped working.

After exploring a bit I found out how to enable it again. Click the Microsoft Office Button, click Excel Options, and then click the Advanced tab and then Select the check box that says “Enable fill handle and cell drag-and-drop” and if you want to be alerted before overwriting an already filled cell then Select “Alert before overwriting cells” too.

I am not exactly sure why this problem came at the first place & I am still trying to reproduce the steps but until then this solution will be quite handy 🙂