It depends on your file path. For me, the current directory was [project]\bin\Debug
, so I had to move to the parent folder twice.
Image image = Image.FromFile(@"..\..\Pictures\"+text+".png");
this.pictureBox1.Image = image;
To find your current directory, you can make a dummy label called label2 and write this:
this.label2.Text = System.IO.Directory.GetCurrentDirectory();