Why might a galvanic cell go dead?

The anode is fully oxidized, or the cathode solution is depleted.
A galvanic cell functions by separating a redox reaction, where one metal is oxidized (loses electrons) and another is reduced (gains electrons). Here’s an example reaction:
##Zn(s) + Cu^(2+)(aq) -> Zn^(2+)(aq) + Cu(s)##
In this reaction, the zinc starts as a solid metal and ends as an ion in solution. The copper starts as an ion in solution and ends as a solid metal. The setup for a galvanic cell is pretty complex (), but the key part is that electrons leave the zinc bar, travel up the wire, and end up meeting up with the copper ions at the copper bar.
For this reaction to continue, there must be solid zinc. However, as the reaction proceeds, the solid zinc keeps giving away electrons and becoming an ion. If there’s no more solid zinc, there’s no more cell. Similarly, if there are no more copper ions left to accept the electrons, there’s no more cell.