Move your mouse over where it was before it was hidden and it should appear. then right click on a blank space on it, click Properties and uncheck autohide.
if that doesn't work, try this: move your mouse around where the panel used to be and look in the corners of your screen for the unhide arrow and click it to unhide it.
This worked for me with gnome under Ubuntu Gutsy: https://answers.launchpad.net/ubuntu/+source/gnome-panel/+question/1170
Control Panel: Folder Options, advanced, click "show hidden files" click OK or APPLY. Close
Pressing and holding the Ctrl key and holding the Shift key and pressing the 8 key on the main keyboard will show what are known as the special characters. This will include spaces, tabs, paragraph marks and hidden text. It will appear with a dotted line under it. Pressing the same combination again will hide them again.
If your taskbar (also known as the panel) is missing in Ubuntu, you can restore it by pressing Alt + F2, typing gnome-panel, and hitting Enter. Alternatively, you can open a terminal and run the command gnome-panel & to bring it back. If you're using a different desktop environment, such as Xfce or KDE, the method may vary slightly, so make sure to check the specific commands for your environment.
Zichtbaar maken
Xubuntu and Ubuntu are two different versions of Ubuntu. (Ubuntu has GNOME.)
try run gnome-panel in the run dialogue (alt+f2)
You can select the columns around the hidden columns and either widen the cells or pick the Unhide option from the menus or ribbon.You can select the columns around the hidden columns and either widen the cells or pick the Unhide option from the menus or ribbon.You can select the columns around the hidden columns and either widen the cells or pick the Unhide option from the menus or ribbon.You can select the columns around the hidden columns and either widen the cells or pick the Unhide option from the menus or ribbon.You can select the columns around the hidden columns and either widen the cells or pick the Unhide option from the menus or ribbon.You can select the columns around the hidden columns and either widen the cells or pick the Unhide option from the menus or ribbon.You can select the columns around the hidden columns and either widen the cells or pick the Unhide option from the menus or ribbon.You can select the columns around the hidden columns and either widen the cells or pick the Unhide option from the menus or ribbon.You can select the columns around the hidden columns and either widen the cells or pick the Unhide option from the menus or ribbon.You can select the columns around the hidden columns and either widen the cells or pick the Unhide option from the menus or ribbon.You can select the columns around the hidden columns and either widen the cells or pick the Unhide option from the menus or ribbon.
Click home tab, click hide and unhide, click unhide sheet. Click home tab, click hide and unhide click hide sheet.
Ubuntu is best, but then I'm biased, as my computers all run Ubuntu!
unhide
In Excel 2013, you can hide a worksheet by right-clicking on the tab of the worksheet you want to hide and selecting "Hide" from the context menu. To unhide a worksheet, right-click on any visible worksheet tab, choose "Unhide," and then select the worksheet you want to display again. Alternatively, you can use the Ribbon by going to the "Home" tab, clicking on "Format" in the Cells group, and selecting "Hide & Unhide" to hide or unhide sheets.