iPhone 4help - photos gone?

[Orlando 2004]

Please can someone help - I'm clueless with technology hence the fact I haven't done any updates on my phone or backed it up. This morning I took some videos & photos if my daughters assembly. My phone froze & the next thing I knew the camera & photo album said library rebuilding all the pics disappeared. I tried turning it off & some photos reappeare in the photo album & all photos were on the camera roll in the main camera but not in photos. I turned the phons off again & now there are only the ones that were showing in photo album in both. (1620 when there were over 3000 Anyone know how I can get them back? I've tried connecting my phone to the laptop but only the 1620 photos are showing - nothing after march this year.