Do you think if I can take my iphone to Apple store, they'll be able to help me out?
Sorry, Apple can't/won't help you. While it is possible to recover data from an iPhone in a state like yours, the process is expensive and not 100%. Such takes specialized software and hardware and most places charge whether they are successful or not. You might be better served by chalking this up to experience & moving on.
First, check if their physical footprint still exists. Go to Settings > General > Usage and check the amount of storage available, do you notice that there is a lot of used storage ? You can also check it through iTunes, which might show used memory labeled as Other.
I lost all my pictures and videos after jailbreaking my phone, yet iTunes showed that they are still taking physical memory (labeled as Other - iTunes did not recognise my pics or vids anymore). This means they cannot be viewed via Camera Roll but they are still stored in the phone.
To fix that, download iFunBox ( http://www.i-funbox.com ) and use it to locate and extract the images from the phone (no need for iTunes to access the phone). I managed to extract all my photos from the phone to an external USB, which accumulated to over 20GB of photos and videos.
Use this method and you should recover your photos and videos with no previous backup. If your phone shows that there is a lot of empty storage, then your photos might have actually been completely removed.