Looking for a good PC cleanup software – laptop very slow.

I have an Intel Core i3 laptop by Dell which has become very slow recently. I didn't have any anti malware / anti virus installed and now I think there is a lot of malware etc. In my laptop. The laptop is quite a mess now and it has some unnecessary software installed on it which were installed with some other third party applications. Can you suggest me some good PC cleanup software? Will I lose my data if the PC gets cleaned up? Is TuneUp utilities a reliable software?
