previously i got same error like this and i solved like this
con = New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:\NAVEEN KUMAR\DOTNET\windows\WindowsApplication1\WindowsApplication1\123.xls;Extended Properties=""Excel 12.0 Xml;HDR=YES""")
con.Open()
Change connection string like this
connectionstring=" Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:\NAVEEN KUMAR\DOTNET\windows\WindowsApplication1\WindowsApplication1\123.xls;Excel 12.0 Xml;HDR=YES"