How can i restore my background?

My computer has viruses and well my mom won't buy the software like the antivirus stuff!... Well I went onto the computer the day after I was told that my computer had virus by something called Alert something idk there was a pic of a bell (like a red round bell.) And well my desktop picture turned all blue and I can't change it somehow I can only change it to one specific color.... please help

How can i restore my background?house call

The virus has turned off you ability to edit the background.

Start menu -%26gt; Run

Type "regedit" and hit Ok.

Navigate to HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft\Windows \ CurrentVersion \ policies

Delete the ActiveDesktop node

Navigate to HKEY_CURRENT_USER \ SOFTWARE \ Microsoft\Windows \ CurrentVersion \ policies

Delete the ActiveDesktop node

BE VERY CAREFUL USING REGEDIT. You can make your system unusable if you accidentally delete something.