Genealogical dead-ends have long plagued all of us at once time or another. Somehow, you just can't break those ancestral blockades. Fortunately, as technology has evolved so have the choices for discovering family through affordable DNA packages provided by Ancestry.com, 23andme.com, and gedmatch.com.
Recently, I helped a friend discover her biological father after years of unsuccessful searches. She purchased a AncestryDNA from Ancestry.com and waited for her results. By the time, they came in, I had already mapped out her maternal genealogy right down to the German ancestry she didn't know she had, but she was no further to the truth about her father ... that is, until she received a AncestryDNA match of 96% from an unknown relation. The match was with an Italian family as possible 4th cousins. My friend had little information from her mother about her father, even his last name was as questionable as his character. But it was enough for me to eliminate five other possibilities and confirm what I already had suspected. Working with the proper time frames, census records, vital records, and the female generations of this immigrant Italian family, we traced the family by triangulating the data, and found an exact match to her grandmother and confirmed her marriage in the North End of Boston. There we also found her son, a promising ball player who gave up his career for the mob.
There is much more to the story but the point is that old-fashioned genealogical research techniques coupled with DNA can help solve your genealogical roadblocks.