Accidentally locked myself out of my 4th generation ipod (ios 6.1.3) if I restore the ipod will I be able to retrieve my old apps from itunes?

If you restore from backup assuming you have a recent one, you won't lose everything. In regards to snap chat, you may be able to download the last compatible version, but you won't know until you try (some apps let you,some don't ). I don't use snap chat so I don't know. I would say restore, because it's not like you can use the iPod if you are locked out anyway.

When iTunes loads and your iPod shows up. If you click on the iPod in iTunes there should be the option to restore from backup or restore to factory settings. The restore from backup will only be there if you have previously backed up the iPod to the laptop though. Here is a link with more info:Restore your device from an iCloud or iTunes backup - Apple Support

your apps are on your iTunes account now. If you imported your picturesto the computer they will be saved. If you rrestore from the backup a 3:23 today your ipod will revert back to exactly as it was at 3:23 passcode included. But since you now have a backup of the data, you can restore to factory settings (your iPod will be back to how it came out of the box) and then add the apps and music you want.If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled - Apple Support

If you restore from iCloud backup the apps will be automatically downloaded. If you restore from iTunes backup the apps and music have to be in the iTunes library since synced media like apps and music are not included in the backup of the iOS device that iTunes makes.

You can redownload most iTunes purchases by:

Downloading past purchases from the App Store, iBookstore, and iTunes Store

However, it is very likely that some apps have been updated and the updates are not compatible with iOS 6. Thus, if you updated the apps in your iTunes library they will not sync to the iPod.

Starting when iOS 7 was released, Apple now allows downloading the last compatible version of some apps (iOS 4.2.1 and later only)

App Store: Downloading Older Versions of Apps on iOS - Apple Club

App Store: Install the latest compatible version of an app

You first have to download the non-compatible version on your computer. Then when you try to purchase the version on your iPod you will be offered a compatible version if one exists.

You can sync the photos and videos back to the iPod.

iTunes: Syncing photos

iTunes: May be unable to transfer videos to iPhone, iPad, or iPod

iTunes: Frequently asked questions about viewing and syncing videos

Not that if the photos and videos were in your Camera Rol album (taken by or saved to the iPod) the photos will syn to its own album and the videos will sync to the Video app.

If you updated the apps in your iTunes library and the updated apps are not compatible with iOS 6 they will not sync. yo will have to:

Starting when iOS 7 was released, Apple now allows downloading the last compatible version of some apps (iOS 4.2.1 and later only)

App Store: Downloading Older Versions of Apps on iOS - Apple Club

App Store: Install the latest compatible version of an app

You first have to download the non-compatible version on your computer. Then when you try to purchase the version on your iPod you will be offered a compatible version if one exists.

If the version of SnapChat in you iTunes library is compatible with iOS 6.1.6 then it will sync to the iPod.

So basically if the version in my itunes matches the version I am currently running on my ipod it will sync once I've restored it?

Yes, that is correct

All questions asked in a polite manner are fine, like the ones you asked

if I do the restore to factory settings from my itunes would that delete the apps I have saved to my itunes?

Restoring the iPod does not effect your iTunes library in anyway