how to read boolean value from gridview?

Try reading from disLikedt instead of disLikegr. For example:

bool i = (bool)disLikedt.Rows[0][1];

It depends on the values and on types of data stored in table and grid. Show some details about what is disLikedt.Rows[0][1] or disLikegr.Rows[0].Cells[1].