The day started as any other in the sewers of New York, where the Teenage Mutant Ninja Turtles called home. Donatello was working on a new gadget, Raphael was pounding his training bag, Leonardo was meditating, and Michelangelo was, naturally, raiding the fridge.

Their peaceful day was interrupted by an explosion from Donatello’s lab. A thick cloud of green gas filled the room, causing the turtles to cough and pass out.

When they awoke, they were disoriented. They looked at each other, then at themselves, and realized something was wrong. They had forgotten who they were!

In their confusion, they looked at their colored headbands for cues. But to their dismay, the colors simply didn’t connect with their identities. They were in total chaos!

Leonardo, with the blue headband, thought he was Raphael. Donatello, with purple, believed he was Michelangelo. Raphael, with red, was convinced he was Leonardo, and Michelangelo, with orange, thought he was Donatello.

Seeing the mess, Master Splinter stepped in. His pupils were in disarray, and he could see the confusion clouding their eyes. It was a sight he had never hoped to witness!

Master Splinter attempted to remind them of their identities, recounting their individual strengths and mannerisms. However, his words fell on confused ears. They just couldn’t comprehend.

Frustrated, but unwilling to give up, Master Splinter took a bold decision. He took his cane and with a swift thwack, hit each one on their heads, hoping it'd jog their memories.

Surprisingly, the blows seemed to work. The turtles held their heads, staggered, and then strange things started to happen. Each began to remember snippets of their past.

Leonardo, rubbing his head, picked up a katana and felt a burst of familiarity. The blade felt right in his hands, and he remembered his role as the leader.

Donatello began to tinker with a device on the table and found himself understanding its mechanics. The love of technology came flooding back.

Raphael felt an urge to punch something. Looking around, he found the training bag and started pounding it. The release of aggression felt natural, and he knew he was the team’s muscle.

Michelangelo found himself drawn towards the fridge. As he munched on some leftover pizza, he felt a sense of joy and knew he was the party dude.

Seeing the turtles fall back into their usual behavior, Master Splinter let out a sigh of relief. However, he knew they had to ensure something like this doesn't happen again.

He decided they should always carry a reminder of their identities. Master Splinter gave them each a medallion inscribed with their initials to wear with their bandanas.

The turtles agreed, the recent confusion was an experience they did not want to repeat. Now equipped with their medallions, they felt secure and proud of their identities.

Despite the initial chaos, the turtles learned a valuable lesson that day. They understood the importance of their individuality and how it made them stronger as a team.

As the day ended, the sewers returned to its usual calm. Leonardo meditated, Donatello tinkered, Raphael trained, and Michelangelo enjoyed his pizza, each content in their identity.

And above all, Master Splinter watched over them, satisfied that his unique students were back to being themselves. It was once again, a normal day in the sewers.

From then on, whenever they put on their bandanas, they’d feel the medallions and remember who they were. It wasn't just a team of turtles; it was Leonardo, Donatello, Raphael, and Michelangelo.

The medallions did more than just remind them of their names; they reminded them of their unity in diversity, their strength, and their bond as brothers.

The experience made them appreciate each other even more. Each turtle brought something unique to the table, and it was this uniqueness that made them a formidable team.

Thus, what started as a confusing, chaotic day turned into a vital lesson about self-identity and teamwork. Indeed, it was a day they would never forget, even if they tried.

And to ensure they didn't forget, there was always Master Splinter's cane. A reminder that a slight wobble in memory could be corrected with a gentle tap. Well, not so gentle!

So, the 'Lost Bandanas' incident went down in their history. A bizarre memory glitch was turned into a moment of self-discovery, thanks to Master Splinter's wisdom and a little tough love.