Check for Last Used cells

I want to find last used cells

Dim LastRow
        LastRow = sheet.Cells.Find(What:="*", SearchOrder:=xlByRows, SearchDirection:=Microsoft.Office.Interop.Excel.XlSearchDirection.xlPrevious)
        MsgBox(LastRow)

My code not working ..
Please help me

I'm using Find Command. I want to search backwards by Rows but my code not working

Try this maybe.

Dim lr As Long
lr = Cells.Find(What:="*", SearchOrder:=xlRows, _
 SearchDirection:=xlPrevious, LookIn:=xlFormulas).Row