Extract values from the String filed in SQL server

Thanks for responding. I am getting this error "Invalid length parameter passed to the LEFT or SUBSTRING function". I missed one more scenario when I asked for solution i think the error might be because of this not sure though:

Sample data for string: Number of Sales: <Area="XBA" Number="">0</a><XX>END

In this case the OrderNumbers are NULL's and the value is given as 0 for values field. Could please help me in this handling this issue?

Thanks in advance!