A bit of context for you:

U1 is a reference for the PCB designer and assembler (if soldered by hand).

The information you need to find a replacement is the etched text on top of the IC (Integrated circuit, a.k.a “chip”).

If you’re able to read that, put the whole thing into Google or Octopart or your electronics component supplier of choice (Mouser, DigiKey, Farnell, etc). and you should find the IC you need.