have new iPhone 5 and as soon as connected it to iTunes it synced my brother's iPod touch. lost all my photos and contacts and it replaced with his email and photos. way of undoing this or have to reset my phone

I have a new iPhone5 and as soon as i connected it to iTunes it synced my brother's iPod touch. I lost all my photos and contacts and it is replaced with his email and photos. Is there a way of undoing this or do i have to reset my phone?