first thing to do is turn off your computer (maybe even uplug it from the
wall to make sure its off) Let it sit for about 1 minute then turn it back
on. Assuming you have already done that you can press little button that
should be near your space bar that has the windows logo on it. that should
bring up the start menu, if pressing that button does not bring up the start
menu then you could have a deeper issue like a virus or other malware or
some corruption of the operating system files, most thing are fixable but
the fix can be somewhat complicated if you need to repair your operating
system.
don't get to freaked out though. It could also be that someone who shares or
has access to your computer might have either purposefully or not, changed
some settings. try this: right click on any area of the desktop that does
not contain icons (which sound like the whole thing), then in the subsequent
box look for a option that says "arrange icons by" hover over it and you
will get another box, look for "show desktop icons" near the bottom. make
sure there is a checkmark next to that box. if not click to put a check mark
and then your icons should show up.
There is also an autohide option for the startbutton and taskbar. Press the
Windows logo button(lower left on keyboard) then control panel (if control
panel wont open, it's very likely you have a virus) click on classic view in
the upper left, then look for the "taskbar and startmenu" icon and click on
it. again look for the autohide option. if it is checked then uncheck it.
