This article discusses where WSL’s .bashrc and user directory files have gone.
In the older version of WSL, WSL data was stored in an easy-to-find directory like this:
C:\Users\user\AppData\Local\lxss\home\yuis
After a recent update, it appears the directory has changed to a location like this:
C:\Users\%USERNAME%\AppData\Local\Packages\CanonicalGroupLimited.UbuntuonWindows_79rhkp1fndgsc\LocalState\rootfs\
If you still can’t find it, downloading Everything from voidtools and searching for files should make it easy to locate.