It sounds to me like explorer.exe
is not working for you. Since you know how to start processes from Taskmanager with File>New Task (Run),
do it again and this time type: explorer.exe
start explorer.exe and give you back a normal UI with Taskbar and Start Menu. Unfortunately, this is a very
common symptom of malware, and if your UI does not return to normal that is likey the case with your system.
In fairness, there are other causes, so to check, reboot to Safe Mode and check the function of explorer there. If all is well, create a new Admin level user account and log into that. If everything is OK there it is possible to transfer your data and settings over: http://support.micro...om/?kbid=811151
If Safe Mode is no joy, and/or if the new account is goofy, do not pass "Go" on your way to the malware forum. Even if you do find a normal Windows environment in a new account, I strongly suggest going through a full malware removal check anyway. This symptom (no explorer) is so common and suggests such a nasty bug that it is always worth the effort to be assured that the system is, in fact, clean. Why take chances?
What follows is sort of a standard "What to do about malware" post:
I suggest that you follow the procedures outlined here: http://www.geekstogo...-Log-t2852.html
When complete, post a HiJackThis log here: http://www.geekstogo...o-Here-f37.html
Posting a HJT log elsewhere will only delay the help you need.
In your first post, please provide full system specifications and a concise description of the problem.
You will be helped by a trained malware removal specialist.
If problems remain after your helper gives you a clean bill of health,
post back here and we will assist in getting everything sorted.
Good luck, and happy hunting.