Try downloading/using "File Manager HD". Search that name in the Google PlayStore. If the files are still on your device this app will help you manage and move them around. I've been using it for over 6 months now, free version works fine.

Ok, with 'file manager, you now have the ability to "explore" the folders on your tablet. Do not reset your tablet! And do not delete any files folders either until you are sure what's going on.
You don't know what folder these files were 'moved' to yet (you should have just 'copied' them first until you were sure. Invest in a usb flashdrive for backup in the future.).
Start by learning to use FileManager hd' (the hd version is just for tablets). 'Quickpress' on a folder to see what's inside of it, press the 'back' arrow (lower left) to 'back out' of a folder.You can long press on a folder or file until a menu comes up. It'll give you options of what 'actions you can perform relating to the file/folder you 'long pressed' on. The topmost choice will be about "details". Quickpress 'details' to see info about that folder/file. It'll tell you the total size, number of files ia folder contains, when it was last modified, etc. Look for folders that might have a large size and lots of files.

Do you have an SD card installed? They might be there, though they should be on the tablets internal memory or sd card,. Keep looking at what's in folders, use the 'up' button to see different levels of your tablets file directory.

What did you 'move' them from? All those files are probably still on whatever hard drive/memory storage device you moved them off of. You would need some type of file recovery program to do that. As long as you don't overwrite new info/data to that storage device, all that info 'should' still be on it, and will be as long as you don't overwrite those memory sectors with new data.

Good luck, let us know how things are going, ok?

(And next time, don't move any important files until you have at least one good backup made of them. I have micro sd cards, and a few different Sandisk usb flashdrives I use for that. I also bought a 7port usb router from amazon (and a $2 OTG (on the go) cable to use to connect). The hub is ac powered, from http://www.plugable.com (about $25), & it also lets me plug in a cheap usb keyboard/mouse to work with.)

Unless your tablet is malfunctioning, there isn't a need for factory service, and they wouldn't do 'data recovery'. For any chance of recovering your data you should not have done a factory reset, that does clear the memory and puts you back to a 'factory new' condition.

 The thing is you say you 'moved' those files onto the tablet without you knowing exactly where you moved them to (i.e., a specific folder). So they were moved onto the tablets 'internal memory'. Then, you performed the 'reset' which cleared the tablets memory. If that's what happened, the tablet no longer as those files in memory

 Your only chance now at recovering the data is a recovery from wherever you moved them 'from'. Unless it's been overwritten since you moved them off (wherever they were), the information might still be on the original drive that they were moved 'from'. If you know a computer tech friend they may help, or pay an expert to attempt to recover the files. Otherwise, I'm sorry to say, it sounds like you should consider those files gone. It sucks, but what are you going to do? Believe me, it's happened to all of us at one time or another, sruff happens. Good luck to you...