? How much space on HD.... Click My Computer and right click on Drive C:
Choose Properties and you should see a pie chart and the amount of free space and the total size all shown there.
Forget "professional cleaning" at this stage, it is almost bound to disappoint you.
Help everyone to help you by saying what version of Windows you are running?
There are a lot a ways to help you, but the information you can give may avoid sending you up a blind alley