Step 1: Recall what a DNA strand is built from.
Think of DNA as a long chain of repeating units called nucleotides, joined one after another. Each single nucleotide, in turn, is made of three separate pieces stuck together: a nitrogen base, a sugar, and a phosphate group. Complete hydrolysis simply means we add water and break every one of these links, so the chain falls apart into its original small pieces.
Step 2: Identify the sugar released.
Since we are hydrolysing DNA and not RNA, the sugar that comes out is 2-deoxy-D-ribose, the sugar missing an oxygen at the second carbon compared to ribose.
Step 3: Identify the acidic part and the bases.
The phosphate linkages break down to give ordinary phosphoric acid, $H_3PO_4$. As for the bases, a DNA sample that contains Thymine is telling us this is genuine DNA, so alongside Thymine we also recover Adenine, Guanine and Cytosine, since these four bases always occur together in DNA.
Step 4: Put the full picture together.
So breaking the DNA chain apart with water hands us back the sugar, the acid, and the four bases it was built from.
\[ \boxed{\text{2-deoxy-D-ribose, phosphoric acid, and the bases Adenine, Guanine, Cytosine, Thymine}} \]