my dock and desktop have disappeared

Go to systems preferences > dock > and look to see if the 'Hide dock automatically' has been checked.

EDIT.

By desk top, do you mean icons usually found there ... or the task bar.

Is the Desktop there, but not the icons?

In your user/home folder. Select Library. Then go to Preferences/com.apple.desktop.plist and com.apple.dock.plist. Move the .plists to your desktop.

Restart the computer and test. If it works okay, delete the plists from the desktop.

If the application is the same, return the .plists to where you got it from, overwriting the newer one.