Ok This Is where I am experienced at, either you can:
1. Go alt+Ctrl+Delete at the same time and wait for a box to open
2. when the box is open Click "file" at the top and then Click "New Task (Run...)"
3. When you get another small box with something to type in, type in "explorer.exe" (without the ")
4. Your Taskbar and Icons will now load, If not your computer is corrupt. If that happens take your computer to your local IT Guy and ask Him to install explorer for you because it is corrupt
Or you Can do This : (You Have to know a bit about your computer)
1. Go to Run Like in Above
2. Now instead of typing "explorer" type in http://www.google.co.za
(or any other web address)
3. Your Default web browser should open. Now type in in the top "C:\" (without ") and your files should open. dont do anything yet
4. Now go Alt+Ctrl+Del and click on the tab "Processes" Find Explorer.exe in that list and click end process.
5. Now In Alt+Ctrl+Del click on the tab "Applications" and end your browser, Normally "Internet Explorer.exe"
6. Restart By going to Alt+Ctrl+Del and clicking "shut down" at the top.
7. This Refreshes your computer and maybe when you have finished restarting you can have your old pc back
P.S If google loads go to http://www.exenerd.com/exe.php?seed=Explorer.exe
at the top and download and run the software. it will make your computer work