How Do I Restore a Save That I Accidentally Overwrote With A Different Save?

[TheBigScreech]

I accidentally saved over my best world with my brother's save that has nothing on it

[Canute]

Basicly i would say, use your brother as punchingbag for a hour.
And create him an own user account at your mashine, so he don't even got access to your safe's.

There are no easy and no 100% way's to recover that.
Do a search for "overwritten files"  and/or read this.
https://www.easeus.com/file-recovery/recover-overwritten-files.html