Link text Box to Combobox in Userform and autoupdate database

hi abhiD,
as an option try this and see if it helps you!

Private Sub cmboMeter_Change()
Dim myName As String, myRange As Range
   
   myName = Me.cmboMeter.Text
   Set myRange = ThisWorkbook.Sheets("sheet4").Range("a:a")
   Set found = myRange.Find(myName, LookIn:=xlValues)
   If Not found Is Nothing Then
      Me.txtRef_1 = found.Offset(, 1)
      Me.units = found.Offset(, 2)
   Else
      Me.txtRef_1 = ""
      Me.units = ""
   End If
End Sub

Private Sub cmdAdd_Click()
Application.ScreenUpdating = False
     
'switch off screen updating to speed up code and prevent screen flickering
  
    
    Dim NextRw As Long
    With Sheets("Sheet4")
        'find next empty row using Column A
        NextRw = .Cells(.Rows.Count, 1).End(xlUp).Row + 1
Dim Wks As Worksheet
    
        Set Wks = ActiveSheet

        'input the textbox entries
        .Cells(NextRw, 1).Value = Me.cmboMeter.Text
        .Cells(NextRw, 2).Value = Me.txtRef_1.Value
        .Cells(NextRw, 3).Value = Me.units.Value
        End With
        
         Me.cmboMeter.Value = ""
         Me.txtRef_1.Value = ""
         Me.units.Value = ""
         Me.cmboMeter.SetFocus
         Application.ScreenUpdating = True

        End Sub

Private Sub UserForm_Initialize()
Dim rList As Range
        With Sheets("Sheet4")
        Set rList = .Range(.Cells(2, 1), .Cells(.Rows.Count, 1).End(xlUp))
    End With
     Me.cmboMeter.List = rList.Value
   
End Sub