What you need to do is to replace the sequence structures and use a state machine architecture. Sequences cannot be interupted and stopped (at least elegantly). Make the first case of the state machine the file read and if the file is incorrect, you specify the next state as the file read again. State machines are basically case statements inside a while loop and the case selector is wired to a string or enum. States are passed between the cases via a shift register or by writing to a queue inside the case. There are numerous examples of state machines available. Check out the example called Queued Message Handler.vi in the examples included with LabVIEW. There are others in the LabVIEW example program database.
