Of American-English origin, the phrase to put the toothpaste back in the tube, and its variants, refer to the impossibility of reverting a situation to how it formerly existed.

This phrase occurs, for example, in ‘A new normal’: Talent landscape will see more changes in 2022, by Lisa Earle McLeod, published in the Bowling Green Daily News (Bowling Green, Kentucky) of Sunday 6^th February 2022:

Just one in four workers said their employer is transparent about salaries, according to a report from Salary.com. And that’s about to change. For example, employers in New York City will soon be required to list the minimum and maximum wages for any role they advertise. Business Insider is also launching a new series, “Salary Journeys,” aimed to demystify pay and compensation. The workforce is recognizing the traditional smoke and mirrors of salary ranges are very rarely working in their favor.
There is no putting the toothpaste back in the tube, people. After years of challenge, change and immense self-reflection, there will not be a “back to normal” in the workplace. And honestly, there shouldn’t be.

The earliest occurrences of the phrase to put the toothpaste back in the tube and variants that I have found are as follows, in chronological order:

1-: From The Crazy Fool, by Donald Ogden Stewart, published in The Courier-Journal (Louisville, Kentucky) of Wednesday 19^th August 1925:

“That strike is over,” said Mr. King, “but you know how these agitators are. And besides, there is a rumor that these particular ones have been sent here by a certain Jack Butterfield.”
“Jack Butterfield!” exclaimed Charlie. “The man who is my rival for the hand of Judith. That must never be,” and he clenched his fist until the white showed.
“Well,” said Mr. King. “I would be on my guard. We can’t be too sure of winning. And when the tooth paste is out of the tube, you can’t put it back. You know that, my boy.”

2-: From the Daily News (New York City, New York) of Thursday 21^st July 1927:

BROADWAY—THE TOUGHEST JOB IN THE WORLD

DO YOU LIKE DANCING?
VERY MUCH. DON’T YOU?

WELL, AS FAR AS I’M CONCERNED, THERE’S ONLY ONE THING IN THE WORLD MORE DIFFICULT THAN DOING A STEP LIKE THIS.
AND WHAT’S THAT?

PUTTING TOOTH PASTE BACK IN THE TUBE AFTER YOU’VE SQUEEZED IT OUT!

3-: From the column “O.O.s” by O.B., by Oscar Bane Keeler (1884-1950), published in The Atlanta Journal (Atlanta, Georgia) of Tuesday 30^th April 1929—the following is about the U.S. amateur golfers George Von Elm (1901-1961) and Bobby Jones (1902-1971):

GEORGE, who evidently is taking more or less seriously the prophecy of a certain California sports writer some years ago, that he (George) would win more major championships in the next five years than Bobby Jones, was all set to have a shot at four major titles in 1929—the British open, the British amateur, the United States open and the United States amateur. He plays at Muirfield in the first of these events next week, and he was to play in the British amateur had it been held on the dates originally announced. But he also intends to play at Winged Foot in the United States open, which starts June 27, and if he played in the British amateur, starting June 10, he would have even less time between the two fixtures than Bobby Jones had when he won the British open and the United States open within the space of 17 days, with the ocean trip between—naturally.
NOBODY can blame George for trying, but since Bobby in the last five years has won seven major championships—four United States amateurs, one United States open, and two British opens, added to his victory in the United States open six years ago—it looks as if the California optimist had laid out for George a task comparable to putting the toothpaste back in the tube or unscrambling an egg.

4-: From the column Roughly Speaking, by John Gould, published in the Wichita Daily Times (Wichita Falls, Texas) of Sunday 5^th October 1930:

Helpfulness

We have always been keenly interested in helpful folks, such as, for instance, the mysterious Mr. X. who is now in our city performing various odds and ends of tasks. Just as soon as he gets through fixing clocks and making dresses [?] and speeches, we are going to consult him about a few little jobs that we have had on our mind for quite a while. Two of them in particular, we believe, will hold him for a while. One of them is how to get 19 cents worth of tooth paste back into the tube after the baby has playfully squeezed it out. The other is how to stop women from chattering at bridge games.
We suppose that when we put these undertakings up to Mr. X., he will suddenly discover that he has an engagement to tackle some tasks that he was about to overlook, such as fixing the pavement at Eighth and Brook so it will stay fixed, showing Wichita Falls how to get soft water, solving the Junior college problem, and raising the price of cotton. He will remember that he has a lot of comparatively simple little jobs like these and he won’t ever get to help us.
Well, there probably is some way to get tooth paste back into the tube, at that.

5-: From the column On Broadway, by Walter Winchell (1897-1972), published in several U.S. newspapers in August 1931—for example in the Evening Courier (Camden, New Jersey) of Thursday the 13^th:

Suggested for the Best Similes Dictionary—Meredith Janner: Hard to do as to replace an overpush of toothpaste back in the tube.