Assuming that you are using a Windows machine, try the following:

1. See if the connections are correct.
2. Press Windows key + P
3. Select duplicate or extend options
4. Even now if the screen does not appear then check if you have powered on the 2nd monitor

Assuming that you are using a Windows machine, try the following:

1. See if the connections are correct.
2. Press Windows key + P.
3. Select duplicate or extend options.
4. Even now if the screen does not appear then check if you have powered on the 2nd monitor.