Sheets Object not working correctly in VBA [closed]

I have used this piece of (crap) code for over 2 years then suddenly today it’s stopped working. When I debug the code when it calls

 Sheets("All Trans").Unprotect

The macro just seems to stop working – I haven’t done any Error Handling sadly. The sheet “All Trans” exists no problem – nothing has change – completely confused. Here is the sull subroutine:

Sub add_entry()
    
If [all_fields].Value Then
    
    res = MsgBox("Method: " & Range("New_Entry").Cells(1, 3) & Chr(13) & "To: " & Range("New_Entry").Cells(1, 4) & Chr(13) & "Amount: " & Format(Range("New_Entry").Cells(1, 5), "#,##0") & Chr(13) & "User: " & Range("New_Entry").Cells(1, 6) & Chr(13) & "Notes: " & Range("New_Entry").Cells(1, 7), vbOKCancel, "New Entry")
    If res = 1 Then
        
        Sheets("All Trans").Unprotect
        
        Range("New_Entry").Copy
        
        With Sheets("All Trans")
            .AutoFilterMode = FALSE
            lastRow = .Range("C" & .Rows.Count).End(xlUp).Row
            .Cells(lastRow + 1, 1).EntireRow.PasteSpecial xlValues
        End With
        
        Sheets("All Trans").Protect
        
        Application.CutCopyMode = FALSE
        
        ' [Method].ClearContents
        '[To_Whom].ClearContents
        [Amount].ClearContents
        ' [User].ClearContents
        [Notes].ClearContents
        
        Sheets("Input").Activate
        Range("G4").Select
        
    Else
        
        MsgBox "Try Again!"
        
    End If
    
Else
    
    MsgBox "Please enter all fields"
    
End If

End Sub

I have tried renaming the sheet etc to no avail.