I had the same issue, can't say I know what caused it, but I just closed Android Studio, renamed the c:\users\MY USERNAME\.gradle
directory to old-.gradle
and then re-launched Android Studio.
Android studio then re-created the directory and automatically downloaded the gradle zip file and set it all up.
Seems to all be fine but to be honest I don't know what this directory is nor what the root cause of the problem was either, so proceed with caution and keep the old .gradle
folder around for a bit until you're happy all is working fine.