|You should be able, to start the TaskManager by pressing CTRL+ALT+DELETE.|
Take a look at the Process tab and search for Explorer.exe.
If it isn't there, you can click on File, New Task and type in explorer.exe.
This should bring up your desktop screen.
After that I suggest to take a look at the eventlog and search for any hint on why the explorer doesn't get started.
Also check, which programs are started automatically during system startup.