What is the best way to validate whether or not information exists in a datagrid. Let me give a situation.

What I'm trying to do here is allow the user to search and sort the dgv based off of the character or string that is he/she inputs into a textbox. The things I want to validate are:

The textbox is not blank, and if not blank has valid information. (easy enough)

The dgv has actually been populated from the dataset!!!!!

The second I can't seem to nail down, regardless of what I use. I have tried using rowcollections, columns.count(), cell, item, and a few other properties all of which either get skipped over by my if statements or throw an index is out of range error. Can anyone give me a hand with this?

Thank you.