Like I said in comment, If you remember saving the file.
You can use below PowerShell Command :
Get-ChildItem -Path "D:" -Filter "*.txt" -Recurse | ? { $_.LastWriteTime -gt (Get-Date).AddDays(-3) }
explaination-
Path = "D:" (D drive - you may change drive letter)
Filtering = "*.txt" (searching for .txt file"
LastWriteTime > "AddDays(-3)"
you may change -3 to the days passed since the file may have been created/modified
this command will search 3 days back.
if you need it to search 5 days back, change -3 to -5.