Random alphanumeric password generator with GOTOs
As a general rule of thumb, any time you feel the need to use goto, take a couple of aspirin and lay down until the feeling passes.  They probably should have been deprecated decades ago.

In this particular case, using a string of allowed characters and randomly picking an index in that string would do away with your goto's.

I think too a StringBuilder would do a lot better for storing the characters than a LinkedList.