lost my iPod and don't know how to get back my photos

Get them back from where?

They will only be where you put them.

If you used photo stream, then look for them there.

If you imported them to your computer, then they will be there.

If you did not put them anywhere but your iPhone, then they are gone.

Sorry

Sorry, but it is impossible.

If you put them in the dropbox (or some-what similar) app, you can recover them.

Mine was stolen and I can only access the photos put in the dropbox app.

Restore another iPod touch, iPad or iPhone from the backup of your lost iPod

iOS: Back up and restore your iOS device with iCloud or iTunes