mpu6050 connection failed

after uploading the program to the arduino which is in the examples named as dmp6... the error shows in the serial monitor "mpu6050 connection failed" ... by the way, i copied the code from a video and simply went through the video but in that in serial monitor ... mpu 6050 connection successfull ... but in my work on serial monitor , it shows unsuccessful error ...
what could be the problem ... please help anyone ...

Have you run the I2C scanner to verify your device is visible on the bus, and at what address?