After meeting with the Cutie Mark Crusaders and their unfortunate teacher, Princess Luna, along with her now younger sister Princess Celestia, leads the way to the library. She hopes to find Twilight Sparkle and the rest of the ponies in order to defeat Discord. As the group approached the library entrance, they hear some loud noises coming from inside. They were puzzled as to what could be happening. When they entered, the group was rather surprised to what was occurring.
 
Spike: Twilight it’s me, Spike! chasing after the filly Twilight  
Twilight Sparkle: GO AWAY! throws books at Spike  
Spike: Just listen to me! blocking the oncoming books  
Twilight Sparkle: NO!!!
 
The group saw Spike trying to calm a now filly Twilight.
 
Apple Bloom: Twilight!?  
Spike: sees the others You guys gotta help with… notices Luna, Celestia, and Cheerilee  
Spike: Princess Luna! Princess Celestia and Cheerilee too!?  
Sweetie Belle: What’s wrong with Twilight?  
Spike: I don’t know! When she came to the library, I found her like this and she doesn’t remember me!  
Scootaloo: What are we waiting for!? Come on, let’s help Spike and see if we can help Twilight snap out of it!  
Apple Bloom: Let’s go girls!
 
The crusaders try to grab hold of Twilight, but they underestimated their chances of catching the filly. Twilight began climbing the book shelves to avoid capture.
 
Sweetie Belle: Twilight get down! You’ll hurt yourself!  
Twilight Sparkle: Leave me alone! throws books at the crusaders  
Apple Bloom: Please Twilight! We wanna help you!  
Twilight Sparkle: I said…
 
But before she could finish, Twilight began losing hold of shelf and fell along with dozens of books.
 
Twilight Sparkle: AAAAHHHH!!!! falling but was stopped in mid-air by Luna’s magic  
The Crusaders: AAHHH! piles of books fall upon the crusaders, but thankfully no major injuries
 
Princess Luna: Stand aside, I shall aid thee in your trouble with the young filly. sets Celestia to the side  
Twilight Sparkle: starts crying Don’t hurt me.  
Princess Luna: Do not fear me young one. I am here to give back what was lost. her horn begins conjure magic
 
Luna places her horn onto Twilight’s forehead as her magic begins to take effect. Within mere seconds, Twilight’s memories and experiences were once more revitalized. Her magic slowly yet steadily returned to her, and her cutie mark appeared again. However, Luna’s magic was not strong enough to counter the effect of the time magic that was cast upon the young student by Discord. Nevertheless, Twilight managed to regain her memories and magic.
 
Twilight Sparkle: Ugh… what’s going on? dazed from the spell  
Spike: Twilight? goes to her aid while carrying Celestia  
Twilight Sparkle: Spike? then notices Luna and the crusaders, as well as Celestia and Cheerilee Wait a minute, Princess Luna? Apple Bloom? Sweetie Belle? Scootaloo? gasp Princess Celestia and Cheerilee!?  
Apple Bloom: Are you girls alright?  
Sweetie Belle: Ungh… I’ve been better. pops up with a dictionary on top of her head  
Scootaloo: Same here.  
Princess Celestia: looks at Twilight with curiousness  
Cheerilee: Ababa!  
Twilight Sparkle: This is some kind of dream?  
Princess Luna: I’m afraid not.
 
Luna informs Twilight about everything that’s been happening
 
Twilight Sparkle: Discord’s behind all of this!?  
Princess Luna: He is. Thou does not remember any knowledge of his involvement?  
Twilight Sparkle: I can’t remember all that well. The last things that I remember before my memories went blank were running back to town from some open field. I also recall seeing the others, but barely noticing them from afar. They all looked disoriented from the looks on their faces. Other than that, I don’t know much else.  
Princess Luna: Very well, in either case we must find the other ponies and retrieve the elements of harmony if we’ll have any chance against Discord.  
Spike: But how will we find them if their memory was affected like Twilight’s? concerned while carrying Celestia  
Princess Luna: With all of us, thou has a greater chance in finding the other ponies. Once they’re found, I shall bring the elements of harmony and together we shall defeat Discord.
 
Nearby, a book opens up and the face of Discord appears once again while no pony notices.
 
Discord: Well, now that the gang is all here, it’s time to get things started.

@SeraphimDawn  
Agreed.

@Background Pony  
Technically, spike is older than them. Also, Luna hasn’t changed

@SeraphimDawn  
Agrees. More please

The CMCs knew something was up when they were suddenly the oldest ponies in the room.

This should be a episode.