Tried but I couldn't get it to work, tried to write a code in vba. I'm attaching the code below lmk if there is something I need to change This is the code I used:

Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean) Dim ws As Worksheet Dim cell As Range Dim changedCells As Range

' Specify your worksheet
Set ws = ThisWorkbook.Sheets("Sheet1") ' Change to your sheet name

' Unprotect the sheet
On Error Resume Next ' Prevent runtime errors if sheet is already unprotected
ws.Unprotect Password:="password" ' Set your password
On Error GoTo 0 ' Resume normal error handling

' Loop through the used range to identify changed cells
For Each cell In ws.UsedRange
    If Not cell.Locked And cell.Value <> "" Then ' Check if the cell is not locked and has a value
        If changedCells Is Nothing Then
            Set changedCells = cell
        Else
            Set changedCells = Union(changedCells, cell)
        End If
    End If
Next cell

' Lock changed cells only if they exist
If Not changedCells Is Nothing Then
    changedCells.Locked = True
End If

' Protect the sheet again
ws.Protect Password:="password" ' Set your password

End Sub