I would recommend using the hd44780 library with the hd44780_I2Cexp i/o class.
There are multiple different h/w designs used on i2c backpacks.
The LiquidCrystal_I2C only works with 1 version of the backpack, if you don't have that version it will not work.
The hd44780 library will auto locate the i2c address and auto detect the pin mappings used on the backpack so that it works with all versions of the backpack.
The hd44780 library can give you a plug and play experience without having to configure anything in the sketch.
You can install the hd44780 library directory from the IDE GUI with no zip files involved.
After you install it you should run the included I2CexpDiag sketch which will test your i2c signals then test the LCD to make sure everything is working.
Documentation is available in the Documentation sketch once the library is installed.
You can also read more about it on the github page here:
--- bill