yes my code just like that ;
Blynk.begin(auth, ssid, pass);
but void loop is written correctly
You’re using Blynk.virtualWrite which is not a good idea
You’re using a sketch designed to run on a non-WiFi device such as an Uno, with an ESP8266 as the WiFi modem.
With this configuration, a serial port on the Uno is used to send data to the ESP8266. When you do this, you need to tell the Blynk library which serial port to use, and this is missing from your Blynk.begin command.
I’d suggest that you start by sharing full details of exactly what hardware you are using, along with the Blynk app and library version that you are using.