Limewire - accidentally downloaded some dodgy pictures?

In 2009 I used a file sharing program to download a lot of music & movies. When I checked through the files there were some odd names which suggested that some of the files contained illegal images eg underage porn, so I deleted them with out viewing them, but carried on using lime wire to download music etc while being really careful.

I deleted limewire after about a year because it gave my laptop a virus. I'm wondering if the downloads will be on my ISP history and if I should worry about prosecution for downloading the illegal images (definitely not deliberately, I'm a 20 year old straight girl in a happy relationship with a 28 year old guy and was only 16-17 at the time!) I'm also worried that I had a virus back then too which might have made my Internet activity look even more dodgy if that is impossible and at the time I had an unprotected wireless network.

I haven't got my laptop anymore, I got rid of it 6 months ago because the screen completely broke off so would there be any proof anyway? If this went to court or I got arrested what will the likely sentence or punishment be? I'm not a risk to the public or children & have not got a criminal record. I have absolutely no illegal content on my iPad, iPod or phone either, & never have downloaded even music since this happened.