Read a text file and return value if specified text is found VB .Net 2008

[QuaziBee]

I need to read a text file and if "21" appears I need to start an event that changes the text of a label in my windows form.

A friend suggested I try
Do Until
but I honestly don't know how the do untill returns values.

Beginner programmer here, please be kind.

 

[kmote]

Could you provide some more details about what you are looking for? Do you want to read through a text file and for each instance of the text "21", you want to change the value displayed in a label?