Q: I lost the remote to my apple tv, and the App "Remote" is not working. Suggestions?

Buy a new remote from Apple or an Apple stockist.

if borrow one from friends and or relatives they all work and when you have set remote app up so it works once more you can return it

universal remotes also works though my main appletv remote is my logitech harmony one

If an AppleTv 3 and you have a recent iPhone/iOS device, see this also:

Apple TV (3rd generation): Using an iOS device to set up your Apple TV

HT202788 in the Apple Support will fix this with only your iOS device!  Lifesaver!

https://support.apple.com/en-us/HT202788