Can I restore my pictures

Hello,
yesterday my sister was playing games on our computer and she restarted did a PC recovery. Sadly I lost all the pictures I had. I was very sad because I had pictures of my brothers christening and pictures of my grandparents visit. I wanted to send some pictures of my brother to my grandparents but when I was looking for them I couldn't find them. My sister told me she "accidently" restarted the computer. I was wondering if I can get my pictures back. My hardware is Windows XP. I would be very grateful if u helped me with this problem.