Welcome to the Forum.
First off, please read through the Welcome Topic as that explains how to properly format any posted code here for proper viewing.
As for you issue… Please understand that Blynk uses BT/BLE as a dedicated background link between the MCU and the App… that link is NOT available for you to use directly, as is sometimes normal in other BT/BLE type applications.
And depending on the type of phone you use… Android seems to have better results with BT/BLE then iOS.
BT/BLE also still seems a bit in the Beta stage and can have some significant, quirks and limitations. If at all possible, even using an ESP as shield option is a prefered MCU ↔ Server link.
We highly recommend you start off with much simpler projects until you get a better understanding of both the various commands, and App ↔ Server ↔ MCU communications work.
I also recommend you spend some reading time over on the Arduino site, particularly how to use the Mega’s multiple Hardware Serial ports instead of the much more limited SoftwareSerial.