Aww…
Then I regret to tell you that if nothing happened, you likely lost your text for good.
Lets work on preventing it from ever happening again.
My guess is that you are on a laptop, with a trackpad, and that you accidently selected then overwritten part of your text.
If that is your case, you need to block the trackpad.
See this thread in which I linked to a very convenient app to prevent this :
You may want to equip yourself with a good clipboard manager:
https://ditto-cp.sourceforge.io/
And last, I’ll encourage you to learn about snapshots and backups from the manual.
The only possibility otherwise left, but it is kind of far fetch, is that you’d be using “save as” rather than the normal save/backup procedure, and that having multiple versions of your project (which is bad), you would have added to, and would currently be looking at, the wrong one.