On my 10.5 inch netbook I have debian-jessie with mate-desktop-environment. On one occasion for using the whole desktop screen I hid the bottom panel. I must have messed something in this process. As a result, when I restored the bottom panel it is not recording insertion of a usb stick, nor is it showing any window like a terminal or a browser. I cannot now minimize any opened window and can only open a new window in a new workspace. Oh, the date/time and the workspaces are being shown. How shall I restore the operability of this panel?
Thanks.

Found the solution by trial and error. First Right Click on the Bottom Panel then Pressed for 'Add to Panel' and then 'Window List' and 'Close'. This brought back everything to normal state.