I never changed my homepage but somehow it’s been changed to searchnu.com and it changes back when I try to change it. How can I change my homepage back and how did this get in my computer?

Searchnu.com is affiliated with ask.com.  The ask.com toolbar typically comes in when you download something or update your java.  See the screen shot photo. 

  Whenever you download something, you should examine the boxes that pop-up before you agree to the download because there are almost always tick boxes somewhere that are checked that you must uncheck if you don’t want those toolbars installed on your PC. 

Since searchnu.com and ask.com are considered toolbars, your antivirus usually leaves them alone when it scans your computer.  Technically, since seachnu.com makes it difficult to remove, it is considered by many to be a browser hijacker. 

Try going to add/remove programs and uninstall anything that has to do with the ask.com toolbar.  If you don’t see ask.com or searchqu in the list of programs that are installed, then you can use an antivirus program called Hitman Pro to remove this browser hijacker.  Install it for free from surfright.com, the company who makes it.  You are allowed to use it for free for 30 days.  Once Hitman Pro has finished scanning your computer, you will see searchqu in a list of the malware it found.  See the screen shot photo.

  On the right hand side of each piece of malware or tracking cookie it found, you will see an ignore or delete button.  Click on the pull down arrow and select delete beside all of the searchqu and ask.com results found in the list.  There are usually many.