Can anyone tell me how to clean my computer, to where it will work good, without having to carry it to a shop!?

Someone else mentioned CCleaner, which is another must have.

Here's a list of my 'must haves' (all free)

Spybot Search and Destroy (http://www.safer-networking.org)/

Malware Bytes (http://www.malwarebytes.org)/

HiJack This (see what stuff is hijacking your internet and computer) (http://sourceforge.net/projects/hjt/)

HiJack This - Forum to help tell you what to do with the log Hijack This generates

(http://www.bleepingcomputer.com/forums/f/22/virus-...

Ad Aware by Lavasoft (for virus and malware) http://www.lavasoft.com/products/ad_aware_free.php

And finally, a good free anti virus (only use 1, it's not good to have multiple anti-virus programs on your comp)

AVG (I personally use this) (http://free.avg.com/us-en/homepage)

Avira (another good one) (http://www.avira.com/en/avira-free-antivirus)

And on an off note, a program I can't live without (also free): Unlocker Assistant

(for those times when you try to delete a file, and it's mysteriously "in use" even though you KNOW it's not.)

(http://www.filehippo.com/download_unlocker)

Get a toothbrush, Clean the dust inside the CPU. and also clean the fan.. a dirty computer can slow your computer. You have to do it atleast once in like every 3 months... make sure to clean the fan too. and it could be a problem of your Windows too. maybe its too lag? download Tuneup utilities, it will help defrag and fix bugs and issues in your pc.

downoad ccleaner or advance system care by iobit, i personaly use advance system care. but ccleaner shud do the job