Access a closed drawing

I have a code which changes the dimension style in a drawing

from DimStyle1 to Dimstyle2

Is it possible to change from dimstyle1 to dimstyle2 if dimstyle2 was on a closed drawing. If so What changes should I make to my code.

 
Public Class Class2
<CommandMethod("changedimstyle")> _
Public Sub ChangeDimStyle()
Dim doc As Document = Application.DocumentManager.MdiActiveDocument
Dim db As Database = doc.Database
Dim ed As Editor = doc.Editor
Using trx As Transaction = db.TransactionManager.StartTransaction()
Dim dimTbl As DimStyleTable = trx.GetObject(db.DimStyleTableId, OpenMode.ForRead)
Dim dimDtr As DimStyleTableRecord = trx.GetObject(dimTbl("DimStyle1"), OpenMode.ForRead)
Dim ids As ObjectIdCollection = dimDtr.GetPersistentReactorIds()
For Each objId As ObjectId In ids
If objId.ObjectClass.IsDerivedFrom(RXClass.GetClass(GetType(Dimension))) Then
Dim dimen As Dimension = trx.GetObject(objId, OpenMode.ForWrite)
dimen.DimensionStyleName = "DimStyle2"
End If
Next
trx.Commit()
End Using
End Sub
End Class

Please do not post duplicate threads.